Co-reporter:Wenting Liang;Meiling Zhao;Xueqin Wei;Zhiqiang Yan;Wanhua Wu;Fabrizio Caldera;Francesco Trotta;Dan Su;Zhihui Zhong;Cheng Yang
RSC Advances (2011-Present) 2017 vol. 7(Issue 28) pp:17184-17192
Publication Date(Web):2017/03/17
DOI:10.1039/C6RA28211C
Linear maltodextrin (LM) was cross-linked by pyromellitic dianhydride to afford LM polymers of different cross-linking degrees. When soaked in water, these cross-linked LM polymers (nanosponges (NSs)), evolved into several phases from sol to suspension, then to flowing gel, and finally to rigid gel with an increase in their content. Enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to chiral (E)-isomer (1E), which was employed as a benchmark reaction to quantitatively assess the environmental-to-molecular chirality transfer process, was performed in aqueous media containing these pyromellitate-crosslinked LM-NSs in different phases. The enantiomeric excess (ee) of 1E obtained was relatively insensitive to the phases at least up to the flowing gel phase, but became highly sensitive in the rigid gel phase, exhibiting an abrupt drop in the early rigid gel phase followed by a rapid recovery in the late rigid gel phase. A comparison with the phase-dependent ee profiles previously reported for similar pyromellitate-crosslinked cyclodextrin (CD)- and cyclic nigerosylnigerose (CNN)-NSs revealed that the chiral void space created around the pyromellitate linker in NS is responsible for the dramatic changes in ee in the rigid gel phase, whereas the inherent host cavity in CD/CNN plays only limited roles in the supramolecular photochirogenesis mediated by the sensitizer-crosslinked NSs. The latter insight allows us to further expand the applicable range of the present concept and methodology by employing a much wider variety of oligosaccharides as well as substrates and sensitizing cross-linkers.
Co-reporter:Yuko Kawanami, Shin-ya Katsumata, Masaki Nishijima, Gaku Fukuhara, Kaori Asano, Takeyuki Suzuki, Cheng Yang, Asao Nakamura, Tadashi Mori, and Yoshihisa Inoue
Journal of the American Chemical Society 2016 Volume 138(Issue 37) pp:12187-12201
Publication Date(Web):August 9, 2016
DOI:10.1021/jacs.6b05598
An unprecedented 2:2 complex was shown to intervene in the enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid (A) mediated by a hydrogen-bonding template l-prolinol (P) to accelerate the formation of chiral anti-head-to-head and achiral syn-head-to-head cyclodimers in >99% combined yield with enhanced enantioselectivities of up to 72% ee for the former. The supramolecular complexation and photochirogenic behaviors, as well as the plausible structures, of intervening Am·Pn complexes (m, n = 1 or 2) were elucidated by combined theoretical and experimental spectroscopic, photophysical, and photochemical studies. Furthermore, the photochemical chiral amplification was achieved for the first time by utilizing the preferential 2:2 complexation of A with homochiral P to give normalized product enantioselectivities higher than those of the template used. The present strategy based on the higher-order hydrogen-bonding motif, which is potentially applicable to a variety of carboxylic acids and β-aminoalcohols, is not only conceptually new and expandable to other (photo)chirogenic and sensing systems but also may serve as a versatile tool for achieving photochemical asymmetric amplification and constructing chiral functional supramolecular architectures.
Co-reporter:Mark M. Maturi, Gaku Fukuhara, Koichiro Tanaka, Yuko Kawanami, Tadashi Mori, Yoshihisa Inoue and Thorsten Bach
Chemical Communications 2016 vol. 52(Issue 5) pp:1032-1035
Publication Date(Web):18 Nov 2015
DOI:10.1039/C5CC09107A
A chiral template was constructed from 7-ethynyl-1,5,7-trimethyl-3-azabicyclo[3.3.1]nonan-2-one by Sonogashira cross-coupling with 4,4′′-diiodoterphenyl and was shown to bind the title compound strongly by hydrogen bonding resulting in enantioselectivities of up to 55% enantiomeric excess (ee) in the [4+4] anthracene photodimerization.
Co-reporter:Gaku Fukuhara; Kazuhiro Iida; Yuko Kawanami; Hidekazu Tanaka; Tadashi Mori
Journal of the American Chemical Society 2015 Volume 137(Issue 47) pp:15007-15014
Publication Date(Web):November 13, 2015
DOI:10.1021/jacs.5b09775
Near-perfect stereoselectivity was attained in the diastereodifferentiating [4 + 4] photocyclodimerization of 2-anthracenecarboxylates tethered to a glucose scaffold not by thermodynamically tuning the conformer equilibrium in the ground state but by kinetically controlling the conformer dynamics and reactivity in the excited state, which enabled us, after removal of the scaffold, to obtain a single enantiomer of chiral anti-head-to-head-cyclodimer in >99% optical and 96% chemical yield from an ensemble of four precursor conformers.
Co-reporter:Xueqin Wei, Wenting Liang, Wanhua Wu, Cheng Yang, Francesco Trotta, Fabrizio Caldera, Andrea Mele, Tomoyuki Nishimoto and Yoshihisa Inoue
Organic & Biomolecular Chemistry 2015 vol. 13(Issue 10) pp:2905-2912
Publication Date(Web):22 Dec 2014
DOI:10.1039/C4OB02390K
Cyclic nigerosylnigerose (CNN), a saucer-shaped cyclic tetrasaccharide with a shallow concave surface, was reacted with pyromellitic dianhydride in 1:2 and 1:4 ratios to give two CNN-based polymers of different degrees of crosslinking, both of which swelled upon soaking in water, acting as a ‘nanosponge’ (NS). These NSs evolved several phases from isotropic solution to flowing and rigid gels via suspension by gradually increasing the concentration in water. The CNN-NSs thus prepared effectively mediated the enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to chiral (E)-isomer (1E). The enantiomeric excess (ee) of 1E obtained was a critical function of the solvent composition and the phase evolved at different CNN-NS concentrations in water. In isotropic solution, the enantioselectivity was generally low (−4% to +6% ee) but the chiral sense of 1E was inverted by increasing the methanol content. Interestingly, the product's ee was controlled more dramatically by the phase evolved, as was the case with the cyclodextrin-based nanosponge (CD-NS) reported previously. Thus, the ee of 1E was low in solution and suspension, but suddenly leaped at the phase border of flowing gel and rigid gel to give the highest ee of 22–24%, which are much higher than those obtained with CD-NSs (6–12% ee), revealing the positive roles of the chiral void space formed upon gelation of the crosslinked saccharide polymer.
Co-reporter:Cheng Yang and Yoshihisa Inoue
Chemical Society Reviews 2014 vol. 43(Issue 12) pp:4123-4143
Publication Date(Web):02 Dec 2013
DOI:10.1039/C3CS60339C
Supramolecular photochirogenesis is a rapidly growing interdisciplinary area of science at the boundary of photochemistry, asymmetric synthesis and supramolecular chemistry. The major advantage of supramolecular photochirogenesis over the conventional molecular one is entropic in origin, being achieved by preorganizing substrate(s) in the ground state and manipulating subsequent photochemical transformation by weak but non-transient interactions in chiral supramolecular media. The chirality transfer often becomes more efficient through the cooperative non-covalent interactions and the confinement by host in both ground and excited states. Thus, all of the ground- and excited-state events, including complexation stoichiometry and affinity, chiroptical properties, photophysical behaviour and photochemical reactivity, jointly play pivotal roles in supramolecular photochirogenesis. This may appear to cause complication but in reality expands the range of manipulable factors and available experimental/theoretical tools for elucidating the mechanism and controlling photochirogenic processes both thermodynamically and kinetically, from which some new concepts/methodologies unique to supramolecular photochemistry, such as non-sensitizing catalytic photochirogenesis and wavelength-controlled photochirogenesis, have already been developed. In this review, we will discuss the recent progress and future perspective of supramolecular photochirogenesis.
Co-reporter:Jiabin Yao ; Zhiqiang Yan ; Jiecheng Ji ; Wanhua Wu ; Cheng Yang ; Masaki Nishijima ; Gaku Fukuhara ; Tadashi Mori
Journal of the American Chemical Society 2014 Volume 136(Issue 19) pp:6916-6919
Publication Date(Web):May 2, 2014
DOI:10.1021/ja5032908
In the supramolecular photocyclodimerization of 2-anthracenecarboxylate mediated by 6A,6D-diguanidino-γ-cyclodextrin (CD), the chiral sense and enantiomeric excess of the photoproduct were dynamic functions of temperature and cosolvent to afford the (M)-anti head-to-head cyclodimer in 64% ee in aqueous methanol at −70 °C but the antipodal (P)-isomer in 86% ee in aqueous ammonia at −85 °C, while the corresponding diamino-γ-CD host did not show such unusual photochirogenic behaviors. The ee landscape was very steep against the temperature and sign-inverted against the ammonia content to reveal the opposite temperature dependence at low and high ammonia contents, for which an altered solvent structure and/or guanidinium–carboxylate interaction mode would be responsible.
Co-reporter:Masaki Nishijima, Masato Goto, Mayu Fujikawa, Cheng Yang, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Chemical Communications 2014 vol. 50(Issue 91) pp:14082-14085
Publication Date(Web):22 Jul 2014
DOI:10.1039/C4CC04818K
A simple strategy for choosing optimal bio-supramolecular mediators from the mammalian serum albumin library is proposed for bimolecular photochirogenic reactions. Thus, the enantiodifferentiating photocyclodimerization of 2-anthracencecarboxylate (AC) was optimized in chemical and optical yields, when mediated by porcine and canine serum albumins, both of which bound two AC molecules in the first productive site to give the (P)-enantiomer of syn-head-to-tail-cyclodimer in 69% yield and 89% enantiomeric excess (ee) for the former but the (M)-enantiomer in 77% yield and 97% ee for the latter.
Co-reporter:Yoshiaki Aoki, Nobuo Matsuki, Tadashi Mori, Hiroshi Ikeda, and Yoshihisa Inoue
Organic Letters 2014 Volume 16(Issue 18) pp:4888-4891
Publication Date(Web):September 10, 2014
DOI:10.1021/ol502394g
Solvent, temperature, and excitation wavelength significantly affected the photochemical outcomes of a naphthalene–dicyanoethene system tethered by different number (n) of methylene groups (1–3). The effect of irradiation wavelength was almost negligible for 2a but pronounced for 3a. The temperature dependence and theoretical calculations indicated the diversity of exciplex conformations, an ensemble of which can be effectively altered by changing excitation wavelength to eventually switch the regioselectivity of photoreactions.
Co-reporter:Gaku Fukuhara, Hiroaki Umehara, Saki Higashino, Masaki Nishijima, Cheng Yang, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Photochemical & Photobiological Sciences 2014 vol. 13(Issue 2) pp:162-171
Publication Date(Web):04 Jun 2013
DOI:10.1039/C3PP50127B
2-Hydroxyanthracene (HA) in its neutral form smoothly photocyclodimerized to four stereoisomeric [4 + 4]-cyclodimers, which were isolated and characterized for the first time, whereas the anionic form of HA turned out to be photochemically inert. Enantiodifferentiating photocyclodimerization of HA in the presence of a chiral hydrogen-bonding template (TKS159), γ-cyclodextrin (γ-CDx) and bovine serum albumin (BSA) was examined to afford chiral syn-head-to-tail and anti-head-to-head cyclodimers in modest enantiomeric excesses with TKS159 and γ-CDx, but practically no photocyclodimerization proceeded in the presence of BSA probably due to the ionization of HA in the binding sites.
Co-reporter:Cheng Yang, Qian Wang, Masahito Yamauchi, Jabing Yao, Dayang Zhou, Masaki Nishijima, Gaku Fukuhara, Tadashi Mori, Yu Liu and Yoshihisa Inoue
Photochemical & Photobiological Sciences 2014 vol. 13(Issue 2) pp:190-198
Publication Date(Web):29 Aug 2013
DOI:10.1039/C3PP50255D
Wavelength effects on the enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylate (AC) mediated by native and modified γ-cyclodextrins (CDs) were examined in different solvents at varying temperatures to manipulate the photochirogenic outcomes beyond the thermodynamically determined re/si-enantiotopic face selectivity upon 2:1 complexation of AC with CD in the ground state. Indeed, the stereochemical outcomes, i.e. syn/anti, head-to-tail/head-to-head (HT/HH) and in particular enantiomer ratios, were critical functions of the irradiation wavelength, irrespective of the CD host employed. Furthermore, the wavelength effects observed strongly depended on the host structure, reaction temperature and solvent employed, for which altered stacking geometry of the complexed AC pair is thought to be responsible. By optimizing the irradiation wavelength, chiral host, temperature and solvent, an enantiomeric excess of up to 54 and −37% were achieved for chiral syn-HT and anti-HH dimers.
Co-reporter:Masaki Nishijima, Hidekazu Tanaka, Cheng Yang, Gaku Fukuhara, Tadashi Mori, Viktoria Babenko, Wojciech Dzwolak and Yoshihisa Inoue
Chemical Communications 2013 vol. 49(Issue 79) pp:8916-8918
Publication Date(Web):05 Jul 2013
DOI:10.1039/C3CC44235G
Chiral variants of amyloid fibrils prepared by agitating acidified solutions of bovine insulin at 45 °C not only induced quasi-mirror-imaged circular dichroism spectra upon complexation with 2-anthracenecarboxylate but also gave anti-head-to-head-cyclodimers of the opposite absolute configurations upon photoirradiation.
Co-reporter:Masaki Nishijima, Hanako Kato, Gaku Fukuhara, Cheng Yang, Tadashi Mori, Toru Maruyama, Masaki Otagiri and Yoshihisa Inoue
Chemical Communications 2013 vol. 49(Issue 67) pp:7433-7435
Publication Date(Web):24 Jun 2013
DOI:10.1039/C3CC42656D
Mutant human serum albumins accelerated the photocyclodimerization of 2-anthracenecarboxylate to afford chiral cyclodimers in 75–85% enantiomeric excesses, revealing that the mutations to impair non-productive sites 1 and/or 2 enhanced the substrate binding to site 3 without seriously damaging its inherently high photochirogenic ability.
Co-reporter:Wenting Liang, Cheng Yang, Dayang Zhou, Hitoshi Haneoka, Masaki Nishijima, Gaku Fukuhara, Tadashi Mori, Franca Castiglione, Andrea Mele, Fabrizio Caldera, Francesco Trotta and Yoshihisa Inoue
Chemical Communications 2013 vol. 49(Issue 34) pp:3510-3512
Publication Date(Web):12 Feb 2013
DOI:10.1039/C3CC40542G
Pyromellitate-bridged cyclodextrin nanosponges (CDNSs) evolved from sol into gel state upon gradual increase of the concentration from 0.2 to 2000 mg mL−1 in water. The enantiodifferentiating geometrical photoisomerizations of (Z)-cyclooctene and (Z,Z)-1,3-cyclooctadiene sensitized by CDNS at various concentrations were critically affected by the phase transition of CDNS to afford the corresponding (E)- and (E,Z)-isomers in the highest enantiomeric excesses in the gel state.
Co-reporter:Sebastian Wiegmann;Gaku Fukuhara;Beate Neumann;Hans-Georg Stammler;Jochen Mattay
European Journal of Organic Chemistry 2013 Volume 2013( Issue 7) pp:1240-1245
Publication Date(Web):
DOI:10.1002/ejoc.201201272
Abstract
Starting from an inherently chiral aminomethyl-substituted resorcin[4]arene, a series of urea and amide derivatives were synthesized; these new functionalities extend the macrocycle cavity and introduce new opportunities for chiral recognition. A pair of diastereomeric macrocycles was obtained by introducing (S)-(–)-1-phenylethyl-urea functionalities. Chiral recognition capabilities of the diastereomeric hosts were investigated by circular dichroism spectral titration to reveal modest R/S selectivities of up to 1.4 for mandelic acid and other related carboxylic guests.
Co-reporter:Dr. Masaki Nishijima;Hanako Kato;Dr. Cheng Yang;Dr. Gaku Fukuhara;Dr. Tadashi Mori;Dr. Yasuyuki Araki;Dr. Takehiko Wada;Dr. Yoshihisa Inoue
ChemCatChem 2013 Volume 5( Issue 11) pp:3237-3240
Publication Date(Web):
DOI:10.1002/cctc.201300160
Co-reporter:Dr. Hideo Nishino;Dr. Masahito Hosaka;Dr. Masahiro Katoh;Dr. Yoshihisa Inoue
Chemistry - A European Journal 2013 Volume 19( Issue 41) pp:13929-13936
Publication Date(Web):
DOI:10.1002/chem.201301831
Abstract
The delivery of extraterrestrial organics to primitive Earth is considered to have triggered the origin and subsequent evolution of life. Indeed, enantiomerically enriched amino acids of nonterrestrial origin have been found in carbonaceous meteorites, and enantioselective photodecomposition by circularly polarized light (CPL) in outer space has been proposed to have played some role in the initial enantiomeric bias. To experimentally examine this possibility and elucidate the photoreaction mechanisms, we have studied the photolysis of racemic leucine (rac-Leu) in acidic and neutral ice/water media at 21–298 K with left- and right-CPL in an attempt to detect enantiomerically enriched D- and L-Leu, respectively. Comprehensive product analyses revealed that the CPL-induced deracemization of Leu proceeds in both acidic and neutral ice matrices even at 21 K, and that the main mechanism switches from Norrish-type II γ-hydrogen abstraction to SNi deamination on lowering the temperature. The potential role of the CPL-induced photodecomposition of amino acids as a source of the enantiomer imbalance in meteorites is discussed.
Co-reporter:Yuko Kawanami, Hiroaki Umehara, Jun-ichi Mizoguchi, Masaki Nishijima, Gaku Fukuhara, Cheng Yang, Tadashi Mori, and Yoshihisa Inoue
The Journal of Organic Chemistry 2013 Volume 78(Issue 7) pp:3073-3085
Publication Date(Web):March 5, 2013
DOI:10.1021/jo302818w
Competitive cross-/homo-photocyclodimerization of anthracene (AN) and 2-anthracenecarboxylic acid (AC) mediated by a chiral hydrogen-bonding template (TKS) was investigated under various conditions. The cross-photocyclodimerization was favored by a factor of 4–5 at all temperatures and wavelengths examined to afford the AC-AN cross-dimer in 80–84% yield even at AN/AC = 1 and in 98% yield at AN/AC = 10. The enantiomeric excesses (ee’s) obtained were 27–47% for the homo-dimers and 21–24% for the cross-dimer. The absolute configuration of the cross-dimer was determined by comparing the experimental and theoretical circular dichroism spectra and further correlated with the re/si enantiotopic-face selectivity upon AC-TKS complexation in the ground state. Detailed analyses of the complexation behavior and the fluorescence lifetime and cyclodimerization rate of excited re/si complexes revealed that the product’s ee is critically controlled not only by the relative abundance of the re/si complexes in the ground and excited states but also by their relative photocyclodimerization rate. Crucially, the ground-state thermodynamics and the excited-state kinetics are not synergistic but offsetting in enantiotopic-face selectivity, and the latter overwhelms the former to give the homo- and cross-dimers in modest ee’s. Finally, some practical strategies for enhancing the enantioselectivity in chiral template-mediated photochirogenesis have been proposed.
Co-reporter:Gaku Fukuhara, Tomohiro Nakamura, Yuko Kawanami, Cheng Yang, Tadashi Mori, Hiroyuki Hiramatsu, Yasufumi Dan-oh, Tomoyuki Nishimoto, Kazuo Tsujimoto, and Yoshihisa Inoue
The Journal of Organic Chemistry 2013 Volume 78(Issue 21) pp:10996-11006
Publication Date(Web):October 4, 2013
DOI:10.1021/jo401977f
From a complex mixture of mono- and di-2-anthracenecarboxylic acid (AC) esters of cyclic nigerosylnigerose (CNN), two monoesters (2B and 6A) and four diesters in which AC was introduced on the transannular B/D (2B2D), adjacent A/B and A/D (6A2B and 6A2D), and same B/B (2B3B) nigerose rings were isolated. Possessing two ACs at distant positions, 2B2D and 6A2D showed negative Cotton effects for the 1Bb band, the intensities of which were stronger than that of 6A. 2B2D and 6A2D slowly photocyclodimerized to give HH dimers 3* and 4 with 57% and 81% HH selectivity, respectively, which were appreciably higher than that for 6A (34%), while the enantiomeric excesses (ee’s) of anti-HH dimer 3* were 2% and −18%, respectively. In contrast, 6A2B and 2B3B carrying two ACs on adjacent A and B rings or at vicinal positions on the B ring, respectively, exhibited strong positive CD couplets, the amplitudes of which amounted to 97 and 409 M–1 cm–1, respectively. Upon irradiation, 6A2B afforded 3* with −62% ee and 4 in 96% combined yield, whereas 2B3B gave almost exclusively 3* with −99% ee in 96% yield, likely as a result of the introduction of two ACs at the vicinal positions of the rigid CNN scaffold.
Co-reporter:Anoklase J.-L. Ayitou;Dr. Gaku Fukuhara;Elango Kumarasamy;Dr. Yoshihisa Inoue;Dr. J. Sivaguru
Chemistry - A European Journal 2013 Volume 19( Issue 13) pp:4327-4334
Publication Date(Web):
DOI:10.1002/chem.201203665
Abstract
Enantiospecific axial-to-point chiral transfer in light-induced transformations was efficient under elevated pressure at high temperatures. Model photoreactions with atropisomeric compounds showed higher enantioselectivity in the photoproducts under elevated pressure. The ee values in the photoproducts were rationalized based on the increased stability of optically pure atropisomeric compounds at elevated pressure, even at high temperatures.
Co-reporter:Denis Fuentealba ; Hanako Kato ; Masaki Nishijima ; Gaku Fukuhara ; Tadashi Mori ; Yoshihisa Inoue ;Cornelia Bohne
Journal of the American Chemical Society 2012 Volume 135(Issue 1) pp:203-209
Publication Date(Web):December 13, 2012
DOI:10.1021/ja3081555
The mechanism for the high enantiomeric excess (ee) (80–90%) observed in the photocyclodimerization of 2-anthracenecarboxylate (AC) in the chiral binding sites of human serum albumin (HSA) was studied using fluorescence anisotropy. A long rotational correlation time of 36 ns was observed for the excited states of the ACs bound to the HSA site responsible for the high ee, suggesting that the ACs have restricted rotational mobility in this site. The ACs in this site have the same prochiral face protected by the protein, and this protection is responsible for the high ee observed. These insights provide a strategy for the rational design of supramolecular photochirogenic systems.
Co-reporter:Yuko Kawanami, Shin-ya Katsumata, Jun-ichi Mizoguchi, Masaki Nishijima, Gaku Fukuhara, Cheng Yang, Tadashi Mori, and Yoshihisa Inoue
Organic Letters 2012 Volume 14(Issue 18) pp:4962-4965
Publication Date(Web):September 11, 2012
DOI:10.1021/ol3023402
Circular dichroism (CD) spectral examinations at various host/guest ratios revealed that 2-anthracenecarboxylic acid (AC) forms not only 1:1 but also novel 2:1 hydrogen-bonded/π-stacked complexes with a chiral 4-benzamidoprolinol template (TKS159). The 2:1 complexation is a minor process but causes significant CD spectral changes as a consequence of the exciton coupling interaction of two AC chromophores and greatly accelerates the head-to-head photocyclodimerization to significantly affect the stereochemical outcomes.
Co-reporter:Yasuhiro Nishiyama;Takehiko Wada;Kiyomi Kakiuchi
Chirality 2012 Volume 24( Issue 5) pp:400-405
Publication Date(Web):
DOI:10.1002/chir.22004
Abstract
For mechanistic elucidation of the photosensitized cyclization of 5-hydroxy-1,1-diphenylpentene (1), its methyl ether (4) was synthesized as an unreactive “dummy” substrate and used as a quencher of the sensitizer fluorescence to reveal the intervention of an exciplex intermediate that was unable to detect when reactive substrate 1 was used as a quencher/reactant In the enantiodifferentiating photocyclization of 1 to 2-(diphenylmethyl)tetrahydrofuran (2) sensitized by a chiral saccharide ester of 1,4-naphthalenedicarboxylate (3), the enantiomeric excess (ee) of chiral product 2 obtained in methylcyclohexane (MCH) at 25 °C was significantly enhanced from 20% to 35% upon 10-fold dilution of the sample solution by MCH, for which the reduced solvent polarity, discouraging dissociation of the intervening radical ionic exciplex, is likely to be responsible. Further attempts to microenvironmentally control the photochirogenic reaction and enhance the product's ee through selective solvation of polar cosolvent to the diastereomeric exciplex pair in nonpolar solvent were not successful probably due to the inherently high local polarity around the exciplex of saccharide-appended 3 with alcoholic substrate 1. Chirality 24:400–405, 2012. © 2012 Wiley Periodicals, Inc.
Co-reporter:Cheng Yang;Wenting Liang;Masaki Nishijima;Gaku Fukuhara;Tadashi Mori;Hiroyuki Hiramatsu;Yasufumi Dan-oh;Kazuo Tsujimoto
Chirality 2012 Volume 24( Issue 11) pp:921-927
Publication Date(Web):
DOI:10.1002/chir.22014
ABSTRACT
Isophthalic and terephthalic acid monoesters of cyclic nigerosyl-(16)-nigerose (CNN), a cyclic tetrasaccharide composed of four d-glucopyranosyl residues connected by alternating α-1,3- and α-1,6-linkages, were synthesized as novel chiral supramolecular sensitizers for enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to planar chiral (E)-isomer (1E). Despite the saucer-shaped shallow cavity of CNN that does not immediately guarantee strong ground-state interactions with 1Z, the sensitizer-appended CNNs afforded optically active 1E in such enantiomeric excesses that are much improved than those obtained with an α-cyclodextrin analog and comparable with those obtained with a β-cyclodextrin analog. Interestingly, the enantiomeric excess values obtained were a critical function of temperature and solvent to show an inversion of the product chirality by changing the environmental variants. Nevertheless, all of the differential activation parameters calculated from the temperature-dependent enantiomeric excesses gave an excellent compensatory enthalpy–entropy relationship, indicating an operation of a single enantiodifferentiating mechanism in the present chiral photosensitization with modified CNNs. Chirality 24:921–927, 2012. © 2012 Wiley Periodicals, Inc.
Co-reporter:Yasuhiro Nishiyama, Takehiko Wada, Kiyomi Kakiuchi, and Yoshihisa Inoue
The Journal of Organic Chemistry 2012 Volume 77(Issue 13) pp:5681-5686
Publication Date(Web):June 8, 2012
DOI:10.1021/jo300816w
Enantiodifferentiating photocyclization of 5-hydroxy-1,1-diphenyl-1-pentene (1) sensitized by bis(1,2;4,5-di-O-isopropylidene-α-fructopyranosyl) 1,4-naphthalenedicarboxylate (2) was performed in near-critical and supercritical carbon dioxide media containing organic entrainers to obtain a chiral tetrahydrofuran derivative (3) in enantiomeric excess (ee) higher than those obtained in conventional organic solvents. Interestingly, the entrainer-driven ee enhancement did not depend on the entrainer polarity, which is in contrast to the behavior of the ee observed upon selective solvation in nonpolar organic solvents. This indicates that entrainer clustering around the intervening exciplex is essential in order to keep the intimate sensitizer–substrate contact within the exciplex. Therefore, the clustering itself, rather than its property, is more crucial to prevent the dissociative diffusion to gaseous CO2. The wider allowance in choosing the entrainer enables us to use more “green” solvents for achieving the ee enhancement, while reducing the environmental risk.
Co-reporter:Ryo Maeda ; Takehiko Wada ; Tadashi Mori ; Shigeyuki Kono ; Nobuhiro Kanomata
Journal of the American Chemical Society 2011 Volume 133(Issue 27) pp:10379-10381
Publication Date(Web):June 13, 2011
DOI:10.1021/ja203781f
Photochemical planar-to-planar chirality transfer was effected by using (R)-[10]paracyclophane-12-carboxylates as a planar-chiral sensitizer and (Z)-cyclooctene and (Z,Z)-1,5-cyclooctadiene as prochiral substrates to give a planar-chiral (E)- and (E,Z)-isomer in up to 44% and 87% enantiomeric excess, respectively, the latter of which being the highest ever reported for a sensitized photochirogenic reaction.
Co-reporter:Cheng Yang ; Chenfeng Ke ; Wenting Liang ; Gaku Fukuhara ; Tadashi Mori ; Yu Liu
Journal of the American Chemical Society 2011 Volume 133(Issue 35) pp:13786-13789
Publication Date(Web):August 5, 2011
DOI:10.1021/ja202020x
In contrast to the brilliant success in thermal asymmetric synthesis, precise stereocontrol remains a great challenge in chiral photochemistry because of the lack of effective tools and methodologies for controlling the short-lived, weakly interacting, and highly reactive electronically excited species. In this work, we achieved this goal through the “dual-chiral, dual-supramolecular” photochirogenesis approach, which enabled us to realized dramatic acceleration and perfect stereocontrol in one of the most representative photoreactions. Thus, the [4 + 4] photocyclodimerization of 2-anthracenecarboxylate tethered to an α-cyclodextrin scaffold was accelerated by a γ-cyclodextrin or cucurbit[8]uril host and gave a single enantiomeric cyclodimer (out of four possible chiral and achiral stereoisomers) in up to 98% chemical and 99% optical yield.
Co-reporter:Qian Wang, Cheng Yang, Chengfeng Ke, Gaku Fukuhara, Tadashi Mori, Yu Liu and Yoshihisa Inoue
Chemical Communications 2011 vol. 47(Issue 24) pp:6849-6851
Publication Date(Web):10 May 2011
DOI:10.1039/C1CC11771H
Stereochemical outcomes were critically tuned by excitation wavelength in the supramolecular photocyclodimerization of 2-anthracenecarboxylic acid mediated by native and diamino-modified γ-cyclodextrins.
Co-reporter:Gaku Fukuhara, Mami Imai, Cheng Yang, Tadashi Mori, and Yoshihisa Inoue
Organic Letters 2011 Volume 13(Issue 7) pp:1856-1859
Publication Date(Web):March 1, 2011
DOI:10.1021/ol2003644
6-O-(2-Naphthoyl)curdlan was newly synthesized as a sensitizing polysaccharide host to examine the chiroptical properties, supramolecular complexation, and photochirogenic behavior with (Z,Z)-1,3-cyclooctadiene (1ZZ). The enantiodifferentiating photoisomerization of 1ZZ included and sensitized by this polysaccharide host gave a highly strained chiral (E,Z)-isomer in up to 8.7% enantiomeric excess (ee) in solution and 11.7% ee in the solid state, which are the highest values ever reported for a supramolecular photochirogenesis of 1EZ.
Co-reporter:Gaku Fukuhara, Takahiro Okazaki, Marco Lessi, Masaki Nishijima, Cheng Yang, Tadashi Mori, Andrea Mele, Fabio Bellina, Cinzia Chiappe and Yoshihisa Inoue
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 20) pp:7105-7112
Publication Date(Web):21 Jul 2011
DOI:10.1039/C1OB05716B
Enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid (AC-H) and its lithium salt (AC-Li) in chiral ionic liquid (CIL), (R)-1-(2,3-dihydroxypropyl)-3-methylimidazolium acetate {[(R)-GLYMI][AcO]}, gave a mixture of two head-to-tail (HT) and two head-to-head (HH) cyclodimers in HT/HH ratios of 1.3–1.7 (for AC-H) and 2.2–4.3 (for AC-Li) with low enantiomeric excesses (ee) of 0–3% for chiral syn-HT and anti-HH dimers. In contrast, irradiation of AC-H in an aqueous solution, containing cucurbit[8]uril (CB[8]) as a host and [(R)-GLYMI][AcO] or [(R)-GLYMI][Tf2N] as a modifier of CB portals, afforded the HH dimers in 91–99% selectivity, although the anti-HH dimer was totally racemic. Interestingly, irradiation of AC-H in a dichloromethane solution, containing [(R)-GLYMI][AcO] as a chiral template, led to the formation of the HH-dimers in 98% selectivity with chiral anti-HH dimer in −14% ee, presumably by the dual ligation of two ACs to a CIL through electrostatic and hydrogen-bonding interactions.
Co-reporter:Gaku Fukuhara
Journal of the American Chemical Society 2010 Volume 133(Issue 4) pp:768-770
Publication Date(Web):December 20, 2010
DOI:10.1021/ja110075p
An in situ hybrid complex of Curdlan with water-soluble polythiophene functioned as a highly sensitive and selective saccharide chemosensor in aqueous media, enabling us to discriminate tetrasaccharide acarbose at 1 μM from 24 mono-, di-, tri-, tetra-, and pentasaccharides.
Co-reporter:Gaku Fukuhara, Tomohiro Nakamura, Cheng Yang, Tadashi Mori and Yoshihisa Inoue
Organic Letters 2010 Volume 12(Issue 15) pp:3510-3513
Publication Date(Web):July 6, 2010
DOI:10.1021/ol101362s
Newly synthesized 6-O-(2-anthroyl)amylose (AC-Am; 51% substitution) was photolyzed in (aqueous) DMSO solutions to give HH dimers as major products (after saponification), with modest enantiomeric excesses (ee) of 12−15% and 1−2% for syn-HT and anti-HH dimers, respectively. Addition of γ-cyclodextrin switched the product selectivity to HT and enhanced the ee of syn-HT up to 37%, while the chiral sense of anti-HH was inverted by changing the irradiation temperature, demonstrating usefulness of the dual-supramolecular approach to photochirogenesis.
Co-reporter:Gaku Fukuhara, Cinzia Chiappe, Andrea Mele, Bernardo Melai, Fabio Bellina and Yoshihisa Inoue
Chemical Communications 2010 vol. 46(Issue 20) pp:3472-3474
Publication Date(Web):22 Apr 2010
DOI:10.1039/C002448A
Enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid and its alkali metal salts performed in a chiral ionic liquid gave chiral cyclodimers in good enantiomeric excesses of up to 41%, which is the highest ever reported for a photochirogenic reaction in chiral media.
Co-reporter:Kazuki Bando, Tamotsu Zako, Masafumi Sakono, Mizuo Maeda, Takehiko Wada, Masaki Nishijima, Gaku Fukuhara, Cheng Yang, Tadashi Mori, Tamara C. S. Pace, Cornelia Bohne and Yoshihisa Inoue
Photochemical & Photobiological Sciences 2010 vol. 9(Issue 5) pp:655-660
Publication Date(Web):02 Mar 2010
DOI:10.1039/B9PP00186G
Photocyclodimerization of 2-anthracenecarboxylate mediated by molecular chaperone protein was performed for the first time to afford chiral syn-head-to-tail and anti-head-to-head dimers (2 and 3) in 10% and 16% enantiomeric excess, respectively, with enhanced yields of sterically and electrostatically less-favored head-to-head dimers (3 and 4).
Co-reporter:Ken Tsutsumi Dr.;Yuuki Yanagisawa;Akinori Furutani Dr.;Tsumoru Morimoto Dr.;Kiyomi Kakiuchi ;Takehiko Wada ;Tadashi Mori Dr.
Chemistry - A European Journal 2010 Volume 16( Issue 25) pp:7448-7455
Publication Date(Web):
DOI:10.1002/chem.201000429
Abstract
Upon diastereodifferentiating the [2+2] photocycloaddition of ethylene to a series of p-substituted (−)-8-phenylmenthyl cyclohexenonecarboxylates, the diastereoselectivity was critically controlled by the nature of the substituent introduced to the chiral auxiliary, and the p-nitro-substituted substrate afforded the cycloadducts in 90 % diastereomeric excess (de) and with 97 % isolated yield. Detailed experimental and theoretical conformation analyses revealed that the stacking interaction of the aromatic auxiliary with the cyclohexenone moiety plays the decisive role in determining the substrate conformation and is, therefore, responsible for the dramatic enhancement of the de. Of particular interest, the product de was directly related to the ellipticity of the substrate, enabling us to “predict” the de prior to photoirradiation.
Co-reporter:Nobuya Sawa, Takehiko Wada, Yoshihisa Inoue
Tetrahedron 2010 66(1) pp: 344-349
Publication Date(Web):
DOI:10.1016/j.tet.2009.10.094
Co-reporter:Huibin Qiu, Cheng Yang, Yoshihisa Inoue and Shunai Che
Organic Letters 2009 Volume 11(Issue 8) pp:1793-1796
Publication Date(Web):March 26, 2009
DOI:10.1021/ol900190n
γ-Cyclodextrin (CD) immobilized on a mesoporous silica wall to cap one of the CD portals switched the product distribution of photocyclodimerization of 2-anthrancenecarboxylate from head-to-tail to head-to-head with a significant enhancement of the enantiopurity of the chiral head-to-head product.
Co-reporter:Victor Borovkov
European Journal of Organic Chemistry 2009 Volume 2009( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/ejoc.200890108
Abstract
The cover picture shows a phenomenon of supramolecular chirogenesis in an achiral bisporphyrinoid host upon noncovalent interaction with chiral antipodal guests. This host–guest interaction results in the phenomenon of chirality transfer followed by the induction of circular dichroism in the porphyrin electronic transitions. Details are presented in the Microreview by V. Borovkov and Y. Inoue on p. 189 ff.
Co-reporter:Victor Borovkov
European Journal of Organic Chemistry 2009 Volume 2009( Issue 2) pp:189-197
Publication Date(Web):
DOI:10.1002/ejoc.200800938
Abstract
During the last decade there has been continuously growing interest in the phenomenon of supramolecular chirogenesis, which is a smart combination of chirality and supramolecular chemistry effectively used for investigations of various aspects of living organisms, modern physical and naturalsciences, and also for technological applications. Thanks to their spectral, chemical, and physicochemical properties, porphyrinoids have been found to be one of the best suited classes of compounds for study of this subject. Out of a vast number of the porphyrinoid-based supramolecular systems employed for this purpose, a bisporphyrinoid motif has been shown to be the simplest, yet widely applicable, structural element that satisfies the requirements for the desired chirogenic properties and ease of synthetic methodology. The aim of this microreview is to highlight the advantages and versatility of this type of chromophoric arrangement for supramolecular chirogenesis.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Co-reporter:Debao Xiao;Takehiko Wada
Chirality 2009 Volume 21( Issue 1) pp:110-113
Publication Date(Web):
DOI:10.1002/chir.20617
Abstract
In order to understand the roles of moderately organized media and the factors controlling the chirality transfer in supramolecular photochirogenesis, enantiodifferentiating photoisomerization of (Z)-cyclooctene to the chiral (E)-isomer (1E) has been performed for the first time in liquid crystal (LC) systems such as lyotropic LCs of poly(γ-benzyl-L-glutamate) (PBLG), difluorobenzene derivatives mixture, and thermotropic cholesteryl oleyl carbonate LCs. Basically, the as-employed LCs provided small enantiomer excess (<5%). It is interesting that lyotropic PBLG LCs give contrasting results in cholesteric and nematic mesophases, revealing the importance of the relevant mesophase structure of LC. Selective excitation in achiral difluorobenzene LC doped with a chiral sensitizer facilitates us to conclude that the LC's chiral spatial arrangement is not sufficient or suitable to induce appreciable enantiomeric excess (ee) in the product, but the existence of molecular chirality (of a chiral sensitizer) is essential to afford an optically active (nonracemic) product at least in the present photosensitization system. The photosensitizations in thermotropic LCs further reveal that the product's ee can be manipulated by the LC mesophase not directly but through the sensitizer's conformational changes induced by the supramolecular interactions with the surrounding LC structure. Chirality, 2009. © 2008 Wiley-Liss, Inc.
Co-reporter:Youngkook Kim;Hyunuk Kim;YoungHo Ko Dr.;Narayanan Selvapalam Dr.;MikhailV. Rekharsky Dr. Dr.;Kimoon Kim Dr.
Chemistry - A European Journal 2009 Volume 15( Issue 25) pp:6143-6151
Publication Date(Web):
DOI:10.1002/chem.200900305
Co-reporter:Gaku Fukuhara, Tadashi Mori and Yoshihisa Inoue
The Journal of Organic Chemistry 2009 Volume 74(Issue 17) pp:6714-6727
Publication Date(Web):August 11, 2009
DOI:10.1021/jo9012628
UV−vis, circular dichroism (CD), fluorescence, and NMR spectral studies on the self-inclusion behavior of a newly synthesized sensitizing host, 6-(5-cyanonaphthyl-1-carboamido)-6-deoxy-β-cyclodextrin (1), showed that the appended naphthalene moiety of 1 perches laterally on the cyclodextrin rim in aqueous methanol but is shallowly included and somewhat tilted in its own cavity in water. UV−vis and CD spectral examinations of the complexation of guest substrate 1,1-diphenylpropene (DPP) with host 1 revealed the formation of a stoichiometric 1:1 complex of DPP with 1. The naphthyl fluorescence of 1 was efficiently quenched by the addition of DPP in aqueous solutions of low methanol contents (≤25%) but was less efficiently quenched in more hydrophobic solvents (≥50% methanol), where the fluorophore is not included in the cavity and allows the external attack of DPP to form an exciplex in the bulk solution. Upon irradiation in aqueous solutions of different methanol contents, competitive photoaddition of water and methanol to DPP occurred to give chiral water adduct 3 and methanol adduct 4, favoring the latter product by a factor of 2.5 due to the higher nucleophilicity of methanol. The enantiomeric excess (ee) values of the photoadducts were generally low in highly methanolic solutions, but was greatly improved by increasing the water content to reach 18% ee for 3 and 13% ee for 4 in 10% methanol solution at −10 °C. Interestingly, the ee of methanol adduct 4 was consistently lower than that of water adduct 3 particularly in water-rich solvents, revealing that the product’s ee is not a simple thermodynamic function of the enantioface-selectivity upon complexation of DPP by chiral host 1 but also kinetically controlled by the subsequent photoinduced enantioface-differentiating nucleophilic attack of water and methanol to radical cationic DPP generated photochemically. Compatible with this mechanism, the compensation plot of the differential activation enthalpy versus entropy, which were obtained from the van’t Hoff analysis of the temperature-dependent ee’s obtained in aqueous solutions of varying methanol contents, gave an excellent straight line for water adduct 3 but an unprecedented bent plot for methanol adduct 4, indicating a switching of the mechanism in between 35 and 50% methanol solution. By using high pressure, low temperature, and/or added salt, the ee of water adduct 3 was further enhanced to 24−26%.
Co-reporter:MikhailV. Rekharsky Dr.;Hatsuo Yamamura ;Tadashi Mori ;Akihiro Sato Dr.;Motoo Shiro Dr.;SergeyV. Lindeman Dr.;Rajendra Rathore Dr.;Kouhei Shiba Dr.;YoungHo Ko Dr.;Narayanan Selvapalam Dr.;Kimoon Kim
Chemistry - A European Journal 2009 Volume 15( Issue 8) pp:1957-1965
Publication Date(Web):
DOI:10.1002/chem.200800398
Co-reporter:Chenfeng Ke Dr.;Cheng Yang Dr.;Tadashi Mori Dr.;Takehiko Wada ;Yu Liu
Angewandte Chemie International Edition 2009 Volume 48( Issue 36) pp:6675-6677
Publication Date(Web):
DOI:10.1002/anie.200902911
Co-reporter:Tamara C. S. Pace, Masaki Nishijima, Takehiko Wada, Yoshihisa Inoue and Cornelia Bohne
The Journal of Physical Chemistry B 2009 Volume 113(Issue 30) pp:10445-10453
Publication Date(Web):July 9, 2009
DOI:10.1021/jp903955f
The mechanism for the chirogenesis in the photocyclodimerization of 2-anthracenecarboxylate (AC) bound to human serum albumin (HSA) was investigated using time-resolved fluorescence measurements in the presence of HSA inhibitors and/or an AC singlet excited state quencher. The photophysical studies were correlated with product studies to explain the high enantiomeric excess (ee) observed for the chiral photoproducts. AC binds to HSA in five different binding sites with decreasing affinities. AC bound to the sites with the highest affinity (sites 1 and 2) is unreactive, and the AC can be displaced from these sites by the use of known inhibitors. Time-resolved fluorescence studies isolated a singlet excited state AC bound to a site which exhibited moderate protection from interactions with species in the aqueous phase. This site was assigned to binding site 3, where the chiral photoproducts are formed with a high ee based on the correlation of the photophysical studies with product studies in the presence of a quencher. These results show that the use of inhibitors for multiple binding site proteins is useful to uncover the properties of binding sites for which guest binding has only moderate affinity and where the photophysical characterization of these binding sites is not possible in the absence of inhibitors.
Co-reporter:Mikhail V. Rekharsky, Hatsuo Yamamura, Young Ho Ko, N. Selvapalam, Kimoon Kim and Yoshihisa Inoue
Chemical Communications 2008 (Issue 19) pp:2236-2238
Publication Date(Web):10 Mar 2008
DOI:10.1039/B719902C
Cucurbit[7]uril forms very strong complex with zwitterionic dipeptide Phe–Gly with affinity exceeding 107 M−1 and effectively recognizes peptide sequence of Phe–Gly over Gly–Phe as well as Tyr–Gly over Gly–Tyr and Trp–Gly over Gly–Trp with relative affinities of 23000, 18000 and 2000, respectively.
Co-reporter:Runhua Lu, Cheng Yang, Yujuan Cao, Zhizhong Wang, Takehiko Wada, Wei Jiao, Tadashi Mori and Yoshihisa Inoue
Chemical Communications 2008 (Issue 3) pp:374-376
Publication Date(Web):29 Oct 2007
DOI:10.1039/B714300A
Enantiodifferentiating photoisomerization of (Z)-cyclooctene included and sensitized by m-methoxybenzoyl-β-cyclodextrin gave chiral (E)-isomers in up to 46% enantiomeric excess, which is the highest value ever reported for supramolecular photochirogenesis with analogous hosts, thus demonstrating the crucial role of the sensitizer-spacer moiety in supramolecular photochirogenic systems.
Co-reporter:Gaku Fukuhara, Frank-Gerrit Klärner, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Photochemical & Photobiological Sciences 2008 vol. 7(Issue 12) pp:1493-1500
Publication Date(Web):18 Oct 2008
DOI:10.1039/B812186A
Inherently chiral molecular clip (MC) 2 binds (Z,Z)-1,3-cyclooctadiene (COD) and 1,1-diphenylpropene (DPP) in 4:1:5 THF-MeOH-H2O solution (at 25 °C) with association constants of 8800 and 27000 M−1, respectively. The thermodynamic parameters obtained from the van't Hoff analysis (ΔH° = −96.4 kJ mol−1, ΔS° = −239 J mol−1K−1) reveal that the binding of DPP by MC is strongly driven by the enthalpic gain from hydrophobic and π–π stacking interactions, which is however largely cancelled out by the entropic loss arising from the tight molecular association. Supramolecular photosensitization by MC 2 facilitates the Z–Eisomerization of COD to chiral (E,Z)-isomer in a good E/Z ratio of 0.19 and a low ee of 0.7%, but does not appear to work with DPP probably due to the less-efficient electron transfer in the acceptor–donor–acceptor complex of DPP with MC 2.
Co-reporter:Martin Fleck, Cheng Yang, Takehiko Wada, Yoshihisa Inoue and Thorsten Bach
Chemical Communications 2007 (Issue 8) pp:822-824
Publication Date(Web):20 Nov 2006
DOI:10.1039/B613985J
The intramolecular [2 + 2]-photocycloaddition of the 1,3-divinyl-2-cyclopentyl tetronates 1 was performed under various conditions to give perfect diastereoselectivity and a regioselectivity of up to 85/15 in the presence of γ-cyclodextrin by differentiating the two chemically very similar double bonds of 1.
Co-reporter:Cheng Yang, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
New Journal of Chemistry 2007 vol. 31(Issue 5) pp:697-702
Publication Date(Web):05 Feb 2007
DOI:10.1039/B615353D
Three naphthalene-modified cyclodextrins (CDs) 3–5 were synthesized as supramolecular chiral photosensitizing hosts for enantiodifferentiating photoisomerization of (Z,Z)-1,3-cyclooctadiene (1ZZ) to its E,Z-isomer (1EZ). In aqueous methanolic solutions, β-CD-based sensitizer 4 binds 1ZZ in its chiral cavity much more strongly than α- and γ-CD homologues 3 and 5. Accelerated, often static, fluorescence quenching of these naphthalene-modified CDs was observed upon inclusion of 1ZZ. The photoisomerization of 1ZZ mediated by 3–5 yielded enantiomeric 1EZ in modest yields. The enantiomeric excesses (ee’s) obtained with α- and β-CD-based sensitizers 3 and 4, both of which have relatively small cavities, are less sensitive to temperature, demonstrating the low-entropy nature of the α- and β-CD complexes. In contrast, increasing reaction temperature significantly diminished the product’s ee and even caused a switching of enantioselectivity upon photoisomerization sensitized by γ-CD-based 5, revealing that the entropy factor plays a crucial role in the wide cavity of γ-CD.
Co-reporter:Takeyuki Tanaka;Michael Oelgemöller;Keijiro Fukui;Fumiko Aoki;Tadashi Mori;Takashi Ohno
Chirality 2007 Volume 19(Issue 5) pp:415-427
Publication Date(Web):26 MAR 2007
DOI:10.1002/chir.20391
Ultraviolet absorption (UV) and electronic circular dichroism (ECD) spectra of enantiopure (Z)-8-methoxy-4-cyclooctenone (MCO) were measured in hexane to give a normal single UV absorption band at 298 nm, which is assigned to the carbonyl's π*n transition. Unexpectedly, the ECD spectrum exhibited an apparent couplet pattern with vibrational fine structures. Obviously, the conventional CD exciton coupling mechanism cannot be applied to this bisignate CD signal observed for single-chromophoric MCO. Variable temperature-ECD and vibrational circular dichroism (VCD) spectral measurements, simultaneous UV and ECD spectral band resolution, and density functional theory (DFT) calculations of energy and structure revealed that this apparent CD couplet originates from a rather complicated spectral overlap of more than three conformers of MCO, two of which exhibit mirror-imaged ECD spectra at appreciably deviated wavelengths. In the simultaneous band-resolution analysis, the observed UV and ECD spectra were best fitted to four overlapping bands. Two major conformers were identified by comparing the experimental IR and VCD spectra with the simulated ones, and the other two by comparing the observed UV and ECD spectra with the theoretical ones obtained by time-dependent DFT calculations. It was shown that the combined use of experimental ECD and VCD spectra and theoretical DFT calculations can give a reasonable interpretation for the Cotton effects of the conformationally flexible molecule MCO. Chirality, 2007. © 2007 Wiley-Liss, Inc.
Co-reporter:Gaku Fukuhara;Süreyya Madenci Dr.;Jolanta Polkowska Dr.;Frank Bastkowski Dipl.-Chem.;Frank-Gerrit Klärner Dr.;Yumi Origane;Masayuki Kaneda Dr.;Tadashi Mori Dr.;Takehiko Wada Dr. Dr.
Chemistry - A European Journal 2007 Volume 13(Issue 9) pp:
Publication Date(Web):8 MAR 2007
DOI:10.1002/chem.200790027
Chiral molecular clips were separated by HPLC, and their CD spectra are shown on the cover. These clips, the pseudoenantiomers anti-1 and anti-2, and diastereomer syn-3, were used for assignment of the absolute configurations of anti-1 and anti-2. The space-filling structures of anti-1 and anti-2, also shown, were calculated by conducting a Monte-Carlo conformer search using the force field MMFF94 implemented in SPARTAN '04. For more details, see the Full Paper by Y. Inoue, F.-G. Klärner et al. on page 2473 ff.
Co-reporter:Gaku Fukuhara;Süreyya Madenci Dr.;Jolanta Polkowska Dr.;Frank Bastkowski Dipl.-Chem.;Frank-Gerrit Klärner Dr.;Yumi Origane;Masayuki Kaneda Dr.;Tadashi Mori Dr.;Takehiko Wada Dr. Dr.
Chemistry - A European Journal 2007 Volume 13(Issue 9) pp:
Publication Date(Web):12 JAN 2007
DOI:10.1002/chem.200601585
Inherently chiral molecular clips (MCs), pseudoenantiomeric anti-1 and anti-2, as well as mesoid syn-3, were synthesized by diastereodifferentiating repetitive Diels–Alder reactions of the achiral bisdienophile 6 with chiral diene 5 generated in situ from (−)-menthyl 3,4-bis(dibromomethyl)benzoate 4. These MCs were successfully separated by chiral HPLC to give optically active anti-1 and anti-2 and almost optically inactive syn-3. The structures of anti-1, anti-2, and syn-3 were assigned by high-resolution NMR and the absolute configurations of anti-1 and anti-2 were determined by the exciton-chirality method. Optically active anti-2 can serve as a chiral host. It binds the HCl adduct of D-tryptophan methyl ester (D-TrpOMe⋅HCl) 3.5 times stronger than the L-enantiomer (KD/KL=3.5).
Co-reporter:Hyunuk Kim;Mikhail V. Rekharsky;Tadashi Mori;Simin Liu;Angel E. Kaifer;David Sobransingh;Cheng Yang;Kimoon Kim;Wei Chen;N. Selvapalam;Michael K. Gilson;Lyle Isaacs;Sarvin Moghaddam;Young Ho Ko
PNAS 2007 Volume 104 (Issue 52 ) pp:20737-20742
Publication Date(Web):2007-12-26
DOI:10.1073/pnas.0706407105
The molecular host cucurbit[7]uril forms an extremely stable inclusion complex with the dicationic ferrocene derivative bis(trimethylammoniomethyl)ferrocene
in aqueous solution. The equilibrium association constant for this host-guest pair is 3 × 1015 M−1 (K
d = 3 × 10−16 M), equivalent to that exhibited by the avidin–biotin pair. Although purely synthetic systems with larger association constants
have been reported, the present one is unique because it does not rely on polyvalency. Instead, it achieves its extreme affinity
by overcoming the compensatory enthalpy–entropy relationship usually observed in supramolecular complexes. Its disproportionately
low entropic cost is traced to extensive host desolvation and to the rigidity of both the host and the guest.
Co-reporter:Gaku Fukuhara, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Chemical Communications 2006 (Issue 16) pp:1712-1714
Publication Date(Web):20 Mar 2006
DOI:10.1039/B601674J
Enantiodifferentiating polar photoaddition of methanol to 1,1-diphenylpropene included and sensitized by cyanonaphthalene-modified β-cyclodextrin was examined for the first time to give optically active anti-Markovnikov adduct with accompanying inversion of the chiral sense of the photoproduct by temperature, which is entropic in origin.
Co-reporter:Gaku Fukuhara, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Chemical Communications 2005 (Issue 33) pp:4199-4201
Publication Date(Web):21 Jul 2005
DOI:10.1039/B504948B
In contrast to the photosensitization with a non-methylated analogue, supramolecular photochirogenesis with a novel permethylated mono(6-O-benzoyl)-β-cyclodextrin exhibited a critical dependence of the product's enantiomeric excess upon temperature, and possessed a large differential entropy of activation (−11 J K−1 mol−1) for which the flexible host skeleton is likely to be responsible.
Co-reporter:Tadashi Mori Dr. Dr.
Angewandte Chemie International Edition 2005 Volume 44(Issue 17) pp:
Publication Date(Web):22 MAR 2005
DOI:10.1002/anie.200462071
At the end of its tether: A charge-transfer (CT) dyad with a trimethylene tether forms a folded or extended monomer or a dimer depending on the conditions (see picture). Both dimer formation at low temperatures and monomer confinement by inclusion in a cyclodextrin cavity greatly enhance the anisotropy (g) factor of the CT transition of the complex.
Co-reporter:Takehiko Wada;Kimoon Kim;Yunyan Gao;Kwangsuk Yang
Chirality 2005 Volume 17(Issue S1) pp:S19-S23
Publication Date(Web):25 FEB 2005
DOI:10.1002/chir.20102
By using homochiral mesoporous POST-1 (Scheme 1) as an inherently chiral sensitizing host, supramolecular enantiodifferentiating photoisomerizations of (Z)-cyclooctene (1Z) were performed for the first time to examine the sensitizing ability of the chiral nanopores, walls of which are decorated with pyridine chromophore. The homochiral nanopores of POST-1 crystals were demonstrated to function as an effective chiral-sensitizing cavity to give the optically active (E)-isomer 1E in up to 5% enantiomeric excess (ee), thus expanding the scope of porous material-mediated chirogenesis to both ground and excited electronic states. Chirality 17:S19–S23, 2005. © 2005 Wiley-Liss, Inc.
Co-reporter:Cheng Yang, Gaku Fukuhara, Asao Nakamura, Yumi Origane, Kahee Fujita, De-Qi Yuan, Tadashi Mori, Takehiko Wada, Yoshihisa Inoue
Journal of Photochemistry and Photobiology A: Chemistry 2005 Volume 173(Issue 3) pp:375-383
Publication Date(Web):15 July 2005
DOI:10.1016/j.jphotochem.2005.04.017
6A,6X-Dideoxy-6A,6X-diamino-γ-cyclodextrins (X = B, C, D and E) 5a–d were synthesized as chiral hosts for catalyzing the enantiodifferentiating [4 + 4] photocyclodimerization of 2-anthracenecarboxylic acid (ACA). The electrostatic interaction between 5a–d and ACA efficiently affected the preorganization of two ACA molecules within the γ-CD cavity, and improved the yields of head-to-head cyclodimers. By lowering the reaction temperature or solvent polarity, the electrostatic interaction was further enhanced. The anti-to-syn ratio of the head-to-head isomers gradually increased by changing the host from 5a to 5d (with increasing distance between the two amino groups on the CD rim), demonstrating a good structure–function relationship in this supramolecular photoreaction system. The chiral sense and enantiomeric excess of the photoproducts obtained are significantly affected, and even inverted, by solvent composition and reaction temperature. This temperature- and solvent-controlled chirality switching behavior is proven to originate from the contribution of non-zero differential entropy (ΔΔS‡) in the enantiodifferentiating process. This finding is the first example of a chirality inversion driven by entropy-related factors, such as solvent and temperature, in a non-sensitized asymmetric photoreaction. The sign of ΔΔS‡ was switched by the composition of solvent and exhibited an excellent compensatory relationship against the differential enthalpy (ΔΔH‡), revealing that the photoenantiodifferentiation is governed not only by enthalpy but also by entropy, and also that the enantiodifferentiation mechanism does not vary throughout the whole system, irrespective of the condition changes.
Co-reporter:Tadashi Mori Dr. Dr.
Angewandte Chemie 2005 Volume 117(Issue 17) pp:
Publication Date(Web):22 MAR 2005
DOI:10.1002/ange.200462071
Gemeinsamkeit macht stark: Eine Charge-Transfer(CT)-Diade mit einem Trimethylen-Linker bildet je nach den Bedingungen ein intramolekular gefaltetes oder ein gestrecktes Monomer oder auch ein intermolekulares Dimer (siehe Bild). Sowohl die Dimerbildung bei niedriger Temperatur als auch der Einschluss des Monomers in den Hohlraum eines Cyclodextrins erhöhen den Anisotropiefaktor g des CT-Übergangs des Komplexes erheblich.
Co-reporter:Masayuki Kaneda, Yasuhiro Nishiyama, Sadayuki Asaoka, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Organic & Biomolecular Chemistry 2004 vol. 2(Issue 9) pp:1295-1303
Publication Date(Web):08 Apr 2004
DOI:10.1039/B401108B
Effects of pressure on the enantiodifferentiating methanol addition to 1,1-diphenylpropene (1) sensitized by chiral naphthalenedicarboxylates (3 and 4) were investigated over 0.1–400 MPa. The logarithm of enantiomeric excess (ee) of photoadduct, i.e. 1,1-diphenyl-2-methoxypropane (2), was a linear function of both pressure (P) and temperature (T); further, the product chirality was switched by P in some cases. From the slope of P
− ln(kR/kS) plot, the differential activation volume (ΔΔV‡) was determined for the first time for bimolecular asymmetric photoreactions. The ΔΔV‡ values obtained are mostly larger than those obtained for relevant unimolecular photoreactions, and are a critical function of the nature of the chiral auxiliary and solvent, indicating conformation changes of the intervening diastereomeric exciplex or transition state in different solvents. Indeed, fluorescence spectral examinations of the sensitizer and exciplex under high pressure revealed the existence of exciplexes of variable energy and structure, which may rationalize the different ΔΔV‡ and product ee obtained. A three-dimensional diagram, correlating the ee with P and T, was constructed from the pressure dependence data at different T, from which we may propose an idea of the multidimensional control of asymmetric reaction by the combined use of the entropy-related enviromental factors.
Co-reporter:Victor V. Borovkov Dr.;Isao Fujii Dr.;Atsuya Muranaka;Guy A. Hembury Dr.;Takeyuki Tanaka Dr.;Arnout Ceulemans Dr.;Nagao Kobayashi Dr. Dr.
Angewandte Chemie 2004 Volume 116(Issue 41) pp:
Publication Date(Web):13 OCT 2004
DOI:10.1002/ange.200460965
Ein Zeichen der Zeit: Die röntgenographisch ermittelte Struktur eines 1:1-Pinzettenkomplexes aus einem achiralen Bis(zinkporphyrin) und (R,R)-1,2-Diaminocyclohexan (siehe Bild, Zn rot, N blau) ermöglichte die vollständige und eindeutige Rationalisierung des hocheffizienten Transfers von Chiralitätsinformation von einem optisch aktiven Gast auf einen achiralen Wirt in einem supramolekularen, auf einem Bisporphyrin basierenden System.
Co-reporter:Victor V. Borovkov Dr.;Isao Fujii Dr.;Atsuya Muranaka;Guy A. Hembury Dr.;Takeyuki Tanaka Dr.;Arnout Ceulemans Dr.;Nagao Kobayashi Dr. Dr.
Angewandte Chemie International Edition 2004 Volume 43(Issue 41) pp:
Publication Date(Web):13 OCT 2004
DOI:10.1002/anie.200460965
A sign of the times: A 1:1 tweezer complex consisting of an achiral bis(zinc porphyrin) and (R,R)-1,2-diaminocyclohexane has been characterized by X-ray crystallographic analysis (see picture, Zn red, N blue). This has enabled a full and unambiguous rationalization of the highly efficient transfer of chirality information from an optically active guest to an achiral host in a supramolecular system based on a bisporphyrin to be carried out.
Co-reporter:Yu Liu Dr.;Ying-Wei Yang Dr.;Yun Song Dr.;Heng-Yi Zhang Dr.;Fei Ding;Takehiko Wada Dr.
ChemBioChem 2004 Volume 5(Issue 6) pp:
Publication Date(Web):26 MAY 2004
DOI:10.1002/cbic.200300770
Do you recognise this peptide? Novel 6,6′-(2,2′-dithiobis(2-(benzoylamino)ethylamino))-bridged bis(β-CD), such as the one shown here, showed good to excellent residue selectivities of up to 28 for several nonaromatic dipeptides with the complex stability sequence of Glu-Glu < Gly-Gly < Leu-Gly < Met-Met < Gly-Pro < Gly-Leu, and also a high sequence selectivity of 5.0 for Gly-Leu versus Leu-Gly.
Co-reporter:Tadashi Mori, Hideaki Saito and Yoshihisa Inoue
Chemical Communications 2003 (Issue 18) pp:2302-2303
Publication Date(Web):04 Aug 2003
DOI:10.1039/B305267B
The photodecarboxylation of chiral mesityl alkanoate to mesitylalkane has been studied experimentally/theoretically, and it has been found that the photodecarboxylation proceeds to give the product in >99% enantiomeric excesses under a variety of conditions, indicating no involvement of any radical intermediates, but that the reaction proceeds through the concerted cheletropic extrusion of CO2 from the energetically less-favored s-cis conformation.
Co-reporter:Masayuki Kaneda, Asao Nakamura, Sadayuki Asaoka, Haruhiko Ikeda, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Organic & Biomolecular Chemistry 2003 vol. 1(Issue 24) pp:4435-4440
Publication Date(Web):04 Nov 2003
DOI:10.1039/B310491E
Pressure effects on enantiodifferentiating geometrical photoisomerizations of (Z)-cyclooctene and (Z,Z)-cycloocta-1,5-diene sensitized by chiral benzene-1,2,4,5-tetracarboxylate were investigated over a pressure range of 0.1–750 MPa. Enantiomeric excesses (ee's) of the (E)- and (E,Z)-isomers obtained displayed discontinuous pressure dependencies, affording distinctly different differential activation volumes (ΔΔV‡) for each range, indicating alteration of the enantiodifferentiation mechanism. The switching of ΔΔV‡ occurred at essentially the same pressures of 200 and 400 MPa, which are shared by all the chiral sensitizers, irrespective of the chiral auxiliary employed. Circular dichroism spectral examinations at pressures of up to 400 MPa also revealed that the chiral sensitizers undergo discontinuous conformational changes at 200 MPa, which most likely lead to switching of the enantiodifferentiating sensitization mechanism in the exciplex intermediate.
Co-reporter:Michael Klaes;Ceno Agena;Markus Köhler;Maki Inoue;Takehiko Wada;Jochen Mattay
European Journal of Organic Chemistry 2003 Volume 2003(Issue 8) pp:
Publication Date(Web):27 MAR 2003
DOI:10.1002/ejoc.200390197
Cyclization of resorcinol monoalkyl ethers with aliphatic aldehydes leads to the corresponding racemic mixtures of C4-symmetric rccc-resorc[4]arenes. Separation of these isomers was achieved by mono-O-functionalization of the rccc-2,8,14,20-tetramethylresorc[4]arene (2) with (S)-(+)-10-camphorsulfonyl chloride leading to a diastereomeric mixture of (+)-5a and (−)-5b. After removal of the chiral auxiliary the inherently chiral pure enantiomers (+)-2 and (−)-2 were obtained. Further enantiomerically pure rccc-resorc[4]arenes were obtained by cyclization of (+)-3-[(2S)-2-methylbutoxy]phenol (6) followed by chromatographic separation. The resulting diastereomeric resorc[4]arenes (+)-7a and (−)-7b were examined by CD spectroscopy, showing a perfect mirror image in all solvents examined. This indicates that the resorcarene cavities of (+)-7a and (−)-7b are essentially enantiomers of each other. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Co-reporter:Tadashi Mori, Makoto Takamoto, Takehiko Wada and Yoshihisa Inoue
Photochemical & Photobiological Sciences 2003 vol. 2(Issue 11) pp:1187-1199
Publication Date(Web):14 Jul 2003
DOI:10.1039/B305898K
2,4,6-Trimethylphenyl (mesityl) cyclohexanecarboxylate 1c and related mesityl esters 1a,b and d–f were photodecarboxylated upon irradiation at 254 nm in neutral solvents to give alkylmesitylenes 15 in good yields. In contrast, in the presence of a catalytic amount of acid and a sufficient amount of alcohol, the same compounds underwent facile phototransesterification to afford the corresponding ester 9 and phenol 10 in almost quantitative yields. Photolyses of less-substituted aryl alkanoates such as 2,6-dimethylphenyl (xylenyl), phenyl, 4-methoxyphenyl (4-anisyl) and 4-methoxynaphthyl alkanoates 2–4 and 8 were also investigated to elucidate the reaction mechanism of acid-catalyzed phototransesterification. Irradiation of these esters afforded the corresponding photo-Fries rearrangement products 20–23 both in neutral and acidic acetonitrile with significant acceleration of the processes in the presence of acid. It was elucidated that the photolysis of the esters affords the geminate radical pair 28, which in turn recombines to cyclohexadienone intermediates 29 and 30. Added acid accelerates not only the nucleophilic attack of alcohol to 29 and 30 but also other processes. Prolonged irradiation of the esters in neutral solution led to skeletal rearrangements of the initial product, affording isomeric alkylbenzenes. The phototransposition of cyclohexylmesitylene 15cvia benzvalene intermediates was, on the contrary, retarded under acidic conditions. These acid-controlled competitive photoreactions are representative examples, in which a catalytic amount of acid can alter the fate of reactive intermediates on both ground-state and excited-state surfaces.
Co-reporter:Victor V. Borovkov Dr.;Takunori Harada Dr.;Guy A. Hembury Dr. Dr.;Reiko Kuroda Dr.
Angewandte Chemie 2003 Volume 115(Issue 15) pp:
Publication Date(Web):16 APR 2003
DOI:10.1002/ange.200250524
Die langsame Bildung helicaler J-Aggregate erfolgt bei der Wechselwirkung von (achiralem) Zinkoctaethylporphyrin mit enantiomerenreinem 1-Cyclohexylethylamin im festen Zustand. Diese stabilen chiralen Festkörperaggregate zeigen ausgeprägte optische Aktivität, wie die Circulardichroismus-Spektren erkennen lassen (siehe Bild).
Co-reporter:Victor V. Borovkov Dr.;Takunori Harada Dr.;Guy A. Hembury Dr. Dr.;Reiko Kuroda Dr.
Angewandte Chemie International Edition 2003 Volume 42(Issue 15) pp:
Publication Date(Web):16 APR 2003
DOI:10.1002/anie.200250524
Slow formation of J-type helical aggregates occurs when the simple achiral zinc octaethylporphyrin interacts with enantiopure 1-cyclohexylethylamines in the solid state. These chiral solid-state aggregates exhibit a high degree of optical activity and are remarkably stable, as evidenced in the circular dichroism spectra (see picture).
Co-reporter:Victor V. Borovkov Dr.;Guy A. Hembury Dr. Dr.
Angewandte Chemie International Edition 2003 Volume 42(Issue 43) pp:
Publication Date(Web):4 NOV 2003
DOI:10.1002/anie.200352493
Inducing chirality: The supramolecular interaction of achiral bis(zinc porphyrin) with enantiopure amino acid derivatives in different solvents results in chirality induction. The sign and degree of the circular dichroims is controlled by the solvent polarity (see picture).
Co-reporter:Victor V. Borovkov Dr.;Guy A. Hembury Dr. Dr.
Angewandte Chemie 2003 Volume 115(Issue 43) pp:
Publication Date(Web):4 NOV 2003
DOI:10.1002/ange.200352493
Supramolekulare Chirogenese: Die supramolekulare Wechselwirkung von achiralem Bis(zinkporphyrin) mit enantiomerenreinen Aminosäure-Derivaten führt zur Induktion von Chiralität. Vorzeichen und Größe des Circulardichroismus werden durch die Polarität des Lösungsmittels bestimmt (siehe Bild).
Co-reporter:Masayuki Kaneda, Sadayuki Asaoka, Haruhiko Ikeda, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Chemical Communications 2002 (Issue 12) pp:1272-1273
Publication Date(Web):15 May 2002
DOI:10.1039/B202699F
A hydrostatic pressure of up to 750 MPa induced discontinuous changes in the enantiomeric excess of the (E)-isomer obtained in the enantiodifferentiating photoisomerization of (Z)-cyclooctene and (Z,Z)-cycloocta-1,5-diene, sensitized by chiral benzene-1,2,4,5-tetracarboxylates; indicating a switching of the enantiodifferentiation mechanism, which is attributable to dramatic conformational changes of chiral alkoxycarbonyl auxiliaries at a specific pressure.
Co-reporter:Michael Oelgemöller, Bernhard Brem, Rudolf Frank, Siegfried Schneider, Dieter Lenoir, Norbert Hertkorn, Yumi Origane, Peter Lemmen, Johann Lex and Yoshihisa Inoue
Organic & Biomolecular Chemistry 2002 (Issue 10) pp:1760-1771
Publication Date(Web):14 Aug 2002
DOI:10.1039/B203167A
trans-Stilbene and several cyclic derivatives with hindered free rotation around the C(vinyl)–C(phenyl) single bond were studied by various spectroscopic techniques. Those derivatives which contain 6- or 7-membered aliphatic rings do not exhibit any measurable S1
→ S0 fluorescence. The introduction of two methoxy groups into the 6-membered aliphatic ring derivative accelerates its photoreactivity to such an extent that fluorescence or resonance Raman spectroscopy investigations become impossible. The introduction of aliphatic rings has only a little effect on the frequency of the phenyl-ring stretching vibrations, but pronounced ones on the IR and Raman intensities. The frequency of the vinylic stretching mode is downshifted between 5 and 100 cm−1 except in the case of the derivative with the 4-membered ring, which experiences a hypsochromic shift of 80 cm−1. Only trans-stilbene and its 4-membered cyclic analogues were amenable to fluorescence lifetime measurements. Analysis of VT-NMR spectra of stilbene 7 reveals a barrier of 15.9 kcal mol−1 for equilibration of aliphatic equatorial and axial H-atoms.
Co-reporter:Hatsuo Yamamura;Mikhail Rekharsky;Asako Akasaki;Schuki Araki;Masao Kawai
Journal of Physical Organic Chemistry 2001 Volume 14(Issue 7) pp:416-424
Publication Date(Web):28 JUN 2001
DOI:10.1002/poc.381
The stability constants and standard Gibbs energy, enthalpy and entropy changes for the 1:1 inclusion complexation of N-benzyloxycarbonyl-L-aspartic and -glutamic acids with native β-cyclodextrin (β-CD), mono(6-amino-6-deoxy)-β-CD, mono(6-trimethylammonio-6-deoxy)-β-CD and A,B-, A,C- and A,D-bis(6-trimethylammonio-6-deoxy)-β-CDs were determined in aqueous phosphate buffer (pH 6.9) at 298.15 K by titration microcalorimetry. The supramolecular complex structures were elucidated from 1D and 2D NMR spectra, including ROESY, COSY and HOHAHA techniques. Combining the results obtained from the microcalorimetric and NMR studies, we elucidated not only the detailed complex structures and the thermodynamic consequences, but also the mutual dependence between the complex structure and the overall complexation thermodynamics. Copyright © 2001 John Wiley & Sons, Ltd.
Co-reporter:Yu Liu ;Yong Chen Dr.;Bin Li Dr.;Takehiko Wada Dr.
Chemistry - A European Journal 2001 Volume 7(Issue 12) pp:
Publication Date(Web):5 JUN 2001
DOI:10.1002/1521-3765(20010618)7:12<2528::AID-CHEM25280>3.0.CO;2-9
A series of novel 6,6′-bis(β-cyclodextrin)s linked by 2,2′-bipyridine-4,4′-dicarboxy tethers; that is, 2,2′-bipyridine-4,4′-dicarboxy-bridged bis(6-O-β-cyclodextrin) (2) and N,N′-bis(2-aminoethyl)-2,2′-bipyridine-4,4′-dicarboxamide-bridged (3), N,N′-bis(5-amino-3-azapentyl)-2,2′-bipyridine-4,4′-dicarboxamide-bridged (4) and N,N′-bis(8-amino-3,6-diazaoctyl)-2,2′-bipyridine-4,4′-dicarboxamide-bridged bis(6-amino-6-deoxy-β-cyclodextrin) (5), has been synthesized as cooperative multipoint-recognition receptor models. The inclusion complexation behavior of 2–5 with organic dyes; that is, ammonium 8-anilino-1-naphthalenesulfonate, Brilliant Green, Methyl Orange, Acridine Red, and Rhodamine B, has been investigated in aqueous phosphate buffer solutions (pH 7.20) at 25 °C by means of ultraviolet, fluorescence, and circular dichroism spectrometry as well as by fluorescence lifetime measurements. The spectral titrations gave the complex stability constants (KS) and Gibbs' free energy changes (ΔG°) for the inclusion complexation of 2–5 with the organic dyes and other thermodynamic parameters (ΔH° and ΔS°) for the inclusion complexation of 2–4 with the fluorescent dyes Acridine Red and Rhodamine B. Bis(β-cyclodextrin)s 2–5 displayed higher binding abilities toward most of the examined dye molecules than native β-cyclodextrin 1; this is discussed from the viewpoints of the size/shape-fit concept, the induced-fit interaction, and cooperative, multipoint recognition by the bridging chain and the dual hydrophobic cavities. Thermodynamically, the inclusion complexation of 2–4 with Acridine Red is totally enthalpy driven with a negative or minor positive entropic contribution, but the inclusion complexation with Rhodamine B is mainly entropy-driven with a mostly positive, but occasionally negative, enthalpic contribution; in some cases this determines the complex stability.
Co-reporter:Sarvin Moghaddam ; Cheng Yang ; Mikhail Rekharsky ; Young Ho Ko ; Kimoon Kim ; Yoshihisa Inoue ;Michael K. Gilson
Journal of the American Chemical Society () pp:
Publication Date(Web):February 22, 2011
DOI:10.1021/ja109904u
A dicationic ferrocene derivative has previously been shown to bind cucurbit[7]uril (CB[7]) in water with ultrahigh affinity (ΔGo = −21 kcal/mol). Here, we describe new compounds that bind aqueous CB[7] equally well, validating our prior suggestion that they, too, would be ultrahigh affinity CB[7] guests. The present guests, which are based upon either a bicyclo[2.2.2]octane or adamantane core, have no metal atoms, so these results also confirm that the remarkably high affinities of the ferrocene-based guest need not be attributed to metal-specific interactions. Because we used the M2 method to compute the affinities of several of the new host−guest systems prior to synthesizing them, the present results also provide for the first blinded evaluation of this computational method. The blinded calculations agree reasonably well with experiment and successfully reproduce the observation that the new adamantane-based guests achieve extremely high affinities, despite the fact that they position a cationic substituent at only one electronegative portal of the CB[7] host. However, there are also significant deviations from experiment, and these lead to the correction of a procedural error and an instructive evaluation of the sensitivity of the calculations to physically reasonable variations in molecular energy parameters. The new experimental and computational results presented here bear on the physical mechanisms of molecular recognition, the accuracy of the M2 method, and the usefulness of host−guest systems as test-beds for computational methods.
Co-reporter:Cheng Yang and Yoshihisa Inoue
Chemical Society Reviews 2014 - vol. 43(Issue 12) pp:NaN4143-4143
Publication Date(Web):2013/12/02
DOI:10.1039/C3CS60339C
Supramolecular photochirogenesis is a rapidly growing interdisciplinary area of science at the boundary of photochemistry, asymmetric synthesis and supramolecular chemistry. The major advantage of supramolecular photochirogenesis over the conventional molecular one is entropic in origin, being achieved by preorganizing substrate(s) in the ground state and manipulating subsequent photochemical transformation by weak but non-transient interactions in chiral supramolecular media. The chirality transfer often becomes more efficient through the cooperative non-covalent interactions and the confinement by host in both ground and excited states. Thus, all of the ground- and excited-state events, including complexation stoichiometry and affinity, chiroptical properties, photophysical behaviour and photochemical reactivity, jointly play pivotal roles in supramolecular photochirogenesis. This may appear to cause complication but in reality expands the range of manipulable factors and available experimental/theoretical tools for elucidating the mechanism and controlling photochirogenic processes both thermodynamically and kinetically, from which some new concepts/methodologies unique to supramolecular photochemistry, such as non-sensitizing catalytic photochirogenesis and wavelength-controlled photochirogenesis, have already been developed. In this review, we will discuss the recent progress and future perspective of supramolecular photochirogenesis.
Co-reporter:Gaku Fukuhara, Cinzia Chiappe, Andrea Mele, Bernardo Melai, Fabio Bellina and Yoshihisa Inoue
Chemical Communications 2010 - vol. 46(Issue 20) pp:NaN3474-3474
Publication Date(Web):2010/04/22
DOI:10.1039/C002448A
Enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid and its alkali metal salts performed in a chiral ionic liquid gave chiral cyclodimers in good enantiomeric excesses of up to 41%, which is the highest ever reported for a photochirogenic reaction in chiral media.
Co-reporter:Wenting Liang, Cheng Yang, Dayang Zhou, Hitoshi Haneoka, Masaki Nishijima, Gaku Fukuhara, Tadashi Mori, Franca Castiglione, Andrea Mele, Fabrizio Caldera, Francesco Trotta and Yoshihisa Inoue
Chemical Communications 2013 - vol. 49(Issue 34) pp:NaN3512-3512
Publication Date(Web):2013/02/12
DOI:10.1039/C3CC40542G
Pyromellitate-bridged cyclodextrin nanosponges (CDNSs) evolved from sol into gel state upon gradual increase of the concentration from 0.2 to 2000 mg mL−1 in water. The enantiodifferentiating geometrical photoisomerizations of (Z)-cyclooctene and (Z,Z)-1,3-cyclooctadiene sensitized by CDNS at various concentrations were critically affected by the phase transition of CDNS to afford the corresponding (E)- and (E,Z)-isomers in the highest enantiomeric excesses in the gel state.
Co-reporter:Qian Wang, Cheng Yang, Chengfeng Ke, Gaku Fukuhara, Tadashi Mori, Yu Liu and Yoshihisa Inoue
Chemical Communications 2011 - vol. 47(Issue 24) pp:NaN6851-6851
Publication Date(Web):2011/05/10
DOI:10.1039/C1CC11771H
Stereochemical outcomes were critically tuned by excitation wavelength in the supramolecular photocyclodimerization of 2-anthracenecarboxylic acid mediated by native and diamino-modified γ-cyclodextrins.
Co-reporter:Masaki Nishijima, Masato Goto, Mayu Fujikawa, Cheng Yang, Tadashi Mori, Takehiko Wada and Yoshihisa Inoue
Chemical Communications 2014 - vol. 50(Issue 91) pp:NaN14085-14085
Publication Date(Web):2014/07/22
DOI:10.1039/C4CC04818K
A simple strategy for choosing optimal bio-supramolecular mediators from the mammalian serum albumin library is proposed for bimolecular photochirogenic reactions. Thus, the enantiodifferentiating photocyclodimerization of 2-anthracencecarboxylate (AC) was optimized in chemical and optical yields, when mediated by porcine and canine serum albumins, both of which bound two AC molecules in the first productive site to give the (P)-enantiomer of syn-head-to-tail-cyclodimer in 69% yield and 89% enantiomeric excess (ee) for the former but the (M)-enantiomer in 77% yield and 97% ee for the latter.
Co-reporter:Runhua Lu, Cheng Yang, Yujuan Cao, Zhizhong Wang, Takehiko Wada, Wei Jiao, Tadashi Mori and Yoshihisa Inoue
Chemical Communications 2008(Issue 3) pp:NaN376-376
Publication Date(Web):2007/10/29
DOI:10.1039/B714300A
Enantiodifferentiating photoisomerization of (Z)-cyclooctene included and sensitized by m-methoxybenzoyl-β-cyclodextrin gave chiral (E)-isomers in up to 46% enantiomeric excess, which is the highest value ever reported for supramolecular photochirogenesis with analogous hosts, thus demonstrating the crucial role of the sensitizer-spacer moiety in supramolecular photochirogenic systems.
Co-reporter:Mark M. Maturi, Gaku Fukuhara, Koichiro Tanaka, Yuko Kawanami, Tadashi Mori, Yoshihisa Inoue and Thorsten Bach
Chemical Communications 2016 - vol. 52(Issue 5) pp:NaN1035-1035
Publication Date(Web):2015/11/18
DOI:10.1039/C5CC09107A
A chiral template was constructed from 7-ethynyl-1,5,7-trimethyl-3-azabicyclo[3.3.1]nonan-2-one by Sonogashira cross-coupling with 4,4′′-diiodoterphenyl and was shown to bind the title compound strongly by hydrogen bonding resulting in enantioselectivities of up to 55% enantiomeric excess (ee) in the [4+4] anthracene photodimerization.
Co-reporter:Martin Fleck, Cheng Yang, Takehiko Wada, Yoshihisa Inoue and Thorsten Bach
Chemical Communications 2007(Issue 8) pp:NaN824-824
Publication Date(Web):2006/11/20
DOI:10.1039/B613985J
The intramolecular [2 + 2]-photocycloaddition of the 1,3-divinyl-2-cyclopentyl tetronates 1 was performed under various conditions to give perfect diastereoselectivity and a regioselectivity of up to 85/15 in the presence of γ-cyclodextrin by differentiating the two chemically very similar double bonds of 1.
Co-reporter:Gaku Fukuhara, Takahiro Okazaki, Marco Lessi, Masaki Nishijima, Cheng Yang, Tadashi Mori, Andrea Mele, Fabio Bellina, Cinzia Chiappe and Yoshihisa Inoue
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 20) pp:NaN7112-7112
Publication Date(Web):2011/07/21
DOI:10.1039/C1OB05716B
Enantiodifferentiating photocyclodimerization of 2-anthracenecarboxylic acid (AC-H) and its lithium salt (AC-Li) in chiral ionic liquid (CIL), (R)-1-(2,3-dihydroxypropyl)-3-methylimidazolium acetate {[(R)-GLYMI][AcO]}, gave a mixture of two head-to-tail (HT) and two head-to-head (HH) cyclodimers in HT/HH ratios of 1.3–1.7 (for AC-H) and 2.2–4.3 (for AC-Li) with low enantiomeric excesses (ee) of 0–3% for chiral syn-HT and anti-HH dimers. In contrast, irradiation of AC-H in an aqueous solution, containing cucurbit[8]uril (CB[8]) as a host and [(R)-GLYMI][AcO] or [(R)-GLYMI][Tf2N] as a modifier of CB portals, afforded the HH dimers in 91–99% selectivity, although the anti-HH dimer was totally racemic. Interestingly, irradiation of AC-H in a dichloromethane solution, containing [(R)-GLYMI][AcO] as a chiral template, led to the formation of the HH-dimers in 98% selectivity with chiral anti-HH dimer in −14% ee, presumably by the dual ligation of two ACs to a CIL through electrostatic and hydrogen-bonding interactions.
Co-reporter:Mikhail V. Rekharsky, Hatsuo Yamamura, Young Ho Ko, N. Selvapalam, Kimoon Kim and Yoshihisa Inoue
Chemical Communications 2008(Issue 19) pp:NaN2238-2238
Publication Date(Web):2008/03/10
DOI:10.1039/B719902C
Cucurbit[7]uril forms very strong complex with zwitterionic dipeptide Phe–Gly with affinity exceeding 107 M−1 and effectively recognizes peptide sequence of Phe–Gly over Gly–Phe as well as Tyr–Gly over Gly–Tyr and Trp–Gly over Gly–Trp with relative affinities of 23000, 18000 and 2000, respectively.
Co-reporter:Xueqin Wei, Wenting Liang, Wanhua Wu, Cheng Yang, Francesco Trotta, Fabrizio Caldera, Andrea Mele, Tomoyuki Nishimoto and Yoshihisa Inoue
Organic & Biomolecular Chemistry 2015 - vol. 13(Issue 10) pp:NaN2912-2912
Publication Date(Web):2014/12/22
DOI:10.1039/C4OB02390K
Cyclic nigerosylnigerose (CNN), a saucer-shaped cyclic tetrasaccharide with a shallow concave surface, was reacted with pyromellitic dianhydride in 1:2 and 1:4 ratios to give two CNN-based polymers of different degrees of crosslinking, both of which swelled upon soaking in water, acting as a ‘nanosponge’ (NS). These NSs evolved several phases from isotropic solution to flowing and rigid gels via suspension by gradually increasing the concentration in water. The CNN-NSs thus prepared effectively mediated the enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to chiral (E)-isomer (1E). The enantiomeric excess (ee) of 1E obtained was a critical function of the solvent composition and the phase evolved at different CNN-NS concentrations in water. In isotropic solution, the enantioselectivity was generally low (−4% to +6% ee) but the chiral sense of 1E was inverted by increasing the methanol content. Interestingly, the product's ee was controlled more dramatically by the phase evolved, as was the case with the cyclodextrin-based nanosponge (CD-NS) reported previously. Thus, the ee of 1E was low in solution and suspension, but suddenly leaped at the phase border of flowing gel and rigid gel to give the highest ee of 22–24%, which are much higher than those obtained with CD-NSs (6–12% ee), revealing the positive roles of the chiral void space formed upon gelation of the crosslinked saccharide polymer.
Co-reporter:Masaki Nishijima, Hanako Kato, Gaku Fukuhara, Cheng Yang, Tadashi Mori, Toru Maruyama, Masaki Otagiri and Yoshihisa Inoue
Chemical Communications 2013 - vol. 49(Issue 67) pp:NaN7435-7435
Publication Date(Web):2013/06/24
DOI:10.1039/C3CC42656D
Mutant human serum albumins accelerated the photocyclodimerization of 2-anthracenecarboxylate to afford chiral cyclodimers in 75–85% enantiomeric excesses, revealing that the mutations to impair non-productive sites 1 and/or 2 enhanced the substrate binding to site 3 without seriously damaging its inherently high photochirogenic ability.
Co-reporter:Masaki Nishijima, Hidekazu Tanaka, Cheng Yang, Gaku Fukuhara, Tadashi Mori, Viktoria Babenko, Wojciech Dzwolak and Yoshihisa Inoue
Chemical Communications 2013 - vol. 49(Issue 79) pp:NaN8918-8918
Publication Date(Web):2013/07/05
DOI:10.1039/C3CC44235G
Chiral variants of amyloid fibrils prepared by agitating acidified solutions of bovine insulin at 45 °C not only induced quasi-mirror-imaged circular dichroism spectra upon complexation with 2-anthracenecarboxylate but also gave anti-head-to-head-cyclodimers of the opposite absolute configurations upon photoirradiation.
Co-reporter:Takehiko Wada, Masayuki Shikimi, Yoshihisa Inoue, George Lem and Nicholas J. Turro
Chemical Communications 2001(Issue 18) pp:NaN1865-1865
Publication Date(Web):2001/09/04
DOI:10.1039/B105381G
Enantiodifferentiating photoisomerization of
(Z)-cyclooctene sensitized by (R)- or
(S)-1-methylheptyl benzoate immobilized in zeolite supercages
afforded the respective enantiomer pair, (−)- and
(+)-(E)-isomer (1E) in 5% enantiomeric excess, whilst racemic 1E
was obtained upon homogeneous-phase photosensitization with the same
antipodal sensitizer pair, thus demonstrating for the first time that
chirally modified zeolites not only serve as supramolecular
photosensitizing media but also enhance the original enantiodifferentiating
ability of chiral photosensitizer.
![Benzamide,4-amino-5-chloro-N-[(3S,5S)-1-ethyl-5-(hydroxymethyl)-3-pyrrolidinyl]-2-methoxy-](http://img.cochemist.com/ccimg/142300/142228-17-9.png)
![Benzamide,4-amino-5-chloro-N-[(3S,5S)-1-ethyl-5-(hydroxymethyl)-3-pyrrolidinyl]-2-methoxy-](http://img.cochemist.com/ccimg/142300/142228-17-9_b.png)
![Propanedinitrile, [1-methyl-4-(1-naphthalenyl)butylidene]-](http://img.cochemist.com/ccimg/602400/602330-53-0.png)
![Propanedinitrile, [1-methyl-4-(1-naphthalenyl)butylidene]-](http://img.cochemist.com/ccimg/602400/602330-53-0_b.png)
