Density functional theory (DFT) investigations revealed that 4-cyanopyridine was capable of homolytically cleaving the B−B σ bond of diborane via the cooperative coordination to the two boron atoms of the diborane to generate pyridine boryl radicals. Our experimental verification provides supportive evidence for this new B−B activation mode. With this novel activation strategy, we have experimentally realized the catalytic reduction of azo-compounds to hydrazine derivatives, deoxygenation of sulfoxides to sulfides, and reduction of quinones with B₂(pin)₂ at mild conditions.

Density functional theory (DFT) investigations revealed that 4-cyanopyridine was capable of homolytically cleaving the B−B σ bond of diborane via the cooperative coordination to the two boron atoms of the diborane to generate pyridine boryl radicals. Our experimental verification provides supportive evidence for this new B−B activation mode. With this novel activation strategy, we have experimentally realized the catalytic reduction of azo-compounds to hydrazine derivatives, deoxygenation of sulfoxides to sulfides, and reduction of quinones with B₂(pin)₂ at mild conditions.

A biologically inspired organocatalytic one-pot synthesis of highly functionalized pyridazines, which are ubiquitous structural units in a number of biologically active compounds, has been developed by starting from readily available diazo compounds and Morita–Baylis–Hillman (MBH) carbonates. Under mild reaction conditions, this synthetic route tolerated significant substrate variation to deliver a broad range of substituted products, including CF₃-substituted pyridazines derivatives. Moreover, the introduction of trifluoromethyl groups into the ring of pyridazine could be completed conveniently from 2,2,2-trifluorodiazoethane.

A novel conjugated polymer P-1 incorporating Ru(II) bis(acetylide) complex and borondipyrromethene (BODIPY) moieties in the main chain was synthesized by Pd-catalyzed Sonogashira coupling reaction of diethynyl substituted BODIPY derivative (M-1) and Ru(II) bis(acetylide) complex (M-2), and the reference polymer P-2 was obtained from the same method as preparation of P-1. Compared with P-2, Ru(II)-containing polymer P-1 shows low-bandgap as 0.87 eV from cyclic voltammetry, and obvious redshifts in both UV–vis absorption and fluorescence spectra. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1686–1692

The β-diketonate-based achiral polymer P-1 could be synthesized by the polymerization of 3,7-dibromo-2,8-dimethoxy-5,5-dioctyl-5H-dibenzo[b,d]silole (M1) with (Z)−1,3-bis(4-ethynylphenyl)−3-hydroxyprop-en-1-one (M2) via typical Sonogashira coupling reaction. The β-diketonate unit in the main chain backbone of P-1 can further coordinate with Eu(TTA)_x [TTA⁻ = 4,4,4-trifluoro-1-(thiophen-2-yl)butane-1,3-dionate anion, X = 1, 2, 3] to afford corresponding Eu(III)-containing polymer complexes. The resulting achiral polymer complex P-2 (X = 2) can exhibit strong circular dichroism (CD) response toward both N-Boc-l and d-proline enantiomers. The CD signal was preliminarily attributed to coordination induction between chiral N-Boc-proline and the Eu(III) complex moiety. The linear regression analysis of CD sensing shows a good agreement between the magnitude of molar ellipticity and concentration of chiral N-Boc-l or d-proline, which indicates this kind Eu(III)-containing achiral polymer complex can be used as a chiral probe for enantioselective recognition of N-Boc-l or d-proline enantiomers based on Cotton effect of CD spectra. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3080–3086

A ruthenium-catalyzed direct C7 amidation of indoline CH bonds with sulfonyl azides was developed. This procedure allows the synthesis of a variety of 7-amino-substituted indolines, which are useful in pharmaceutical. The good functional tolerances, as well as the mild conditions, are prominent feature of this method.

Oxidative cyanation of sp³ C–H bonds at the α position of tertiary amines by using TMSCN as the cyanide donor and a novel high-valent rhenium(V) complex was developed. The reaction offers the corresponding α-aminonitriles in good yields with tert-butyl hydroperoxide as the oxidant under mild and acid-free reaction conditions.

A highly efficient, Ag^I/K₂S₂O₈-mediated regioselective phosphonation reaction has been developed by using electron-deficient directing groups. These phosphonation reactions were performed with N,N-dialkylbenzamides, N,N-dialkylbenzenesulfonamides, and nitrobenzene. This method has a broad substrate scope and offers facile construction of C–P bonds.

A new (S)-binaphthalene-based polymer (P-1) was synthesized by the polymerization of 5,5′-((2,5-dibutoxy-1,4-phenylene)bis(ethyne-2,1-diyl))bis(2-hydroxy-3-(piperidin-1-ylmethyl) benzaldehyde (M-1) with (S)-2,2′-dimethoxy-(1,1′-binaphthalene)-3,3′-diamine (M-2) through the formation of a Schiff base; the corresponding chiral polymer (P-2) could be obtained by the reduction of polymer P-1 with NaBH₄. Chiral polymer P-1 exhibited a remarkable “turn-on” fluorescence-enhancement response towards (D)-phenylalaninol and excellent enantioselective recognition behavior with enantiomeric fluorescence difference ratios (ef) as high as 8.99. More importantly, chiral polymer P-1 displays a bright blue fluorescence color change upon the addition of (D)-phenylalaninol under a commercially available UV lamp, which can be clearly observed by the naked eye. On the contrary, chiral polymer P-2 showed weaker enantioselective fluorescence ability towards the enantiomers of phenylalaninol.

A novel chiral (S)-BINAM-based fluorescent polymer sensor was designed and synthesized by the polymerization of 4,4′-((2,5-dibutoxy-1,4-phenylene)bis(ethyne-2,1-diyl))-dibenzaldehyde (M-1) with (S)-2,2′-binaphthyldiamine (S-BINAM, M-2) via Schiff's base formation. The resulting helical chiral polymer sensor exhibited remarkable “turn-on” bright blue fluorescence color upon the addition of trivalent metal ions under a commercially available UV lamp; this change can be clearly observed by the naked eye for direct visual discrimination at low concentration. More importantly, the addition of trivalent metal cations can lead to a most pronounced change of CD spectra of the chiral polymer indicating this kind chiral sensor can also be used as a sole probe for selective recognition of trivalent metal cations based on CD spectra. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4070–4075

A scalable, efficient gold-catalyzed oxidative phosphonation of sp³ CH bonds with various diarylphosphine oxides and dialkyl phosphites has been developed by using air as a sustainable oxidant under mild reaction conditions. It provides an easy access to α-amino phosphonic compounds in high yields with a broad reaction scope. The safe, convenient and environmentally benign process makes this protocol very promising.

A novel polymer P-1 is prepared by the reaction of the monomer 5,5′-divinyl-2,2′-bipyridine and Salen-Zn(II) via Heck cross coupling. Interestingly, P-1 can further incorporate with Eu(TTA)₃·2H₂O to generate copolymer P-2 with two different metal centers. P-2 exhibits exceptional dual emissive properties which can be tuned by excitation wavelength. For example, an orange fluorescence can be obtained when P-2 is excited at 430 nm, whereas a red emission with a huge Stoke shift of 57 nm is observed when it is excited at 345 nm. The high wavelength emission can be attributed to Eu(III) (⁵D₀⁷F₂), which is lit by an effective photoinduced energy transfer process between P-1 and the Eu(TTA)₃ complex. The properties of P-2 have led to a better understanding of the energy transfer process between P-1 and Eu(TTA)₃ moieties.

Modular diboronic acid receptors R-1 and S-1 were synthesized and found to be selective fluorescent chemosensors for saccharides. The fluorescence intensity of R-1 and S-1 increased on addition of saccharides due to the formation of intramolecular 1:1 cyclic complexes. In general, R-1 has higher binding constants and produces a higher fluorescent response with saccharides than S-1.

A new series of π-conjugated chiroptical polymers consisting of styryl BODIPYs moieties and (S)-binaphthyl units has been firstly synthesized via Sonogashira polymerization. The resulting polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV–Vis absorption spectroscopy, cyclic voltammetry (CV), circular dichroism (CD), and density functional theory (DFT) calculations. The chiral polymers have moderate molecular weights, high solubility in commonly solvents and stable chiroptical conformation. And more importantly, the four chiral polymers can exhibit near-infrared (NIR) emissive and good anisotropic fluorescence. We anticipate these chiral NIR polymers will be useful in biological measurements and cellular imaging where NIR emission is beneficial.

A conjugated polymer was synthesized by the polymerization of 4,7-dibromobenzo[2,1,3]thiadiazole (M-1) with tri{1,4-diethynyl-2,5-bis(2-(2-methoxyethoxy)-ethoxy)}-benzene (M-2) via Pd-catalyzed Sonogashira reaction. The polymer shows strong orange fluorescence. The responsive optical properties of the polymer on various metal ions were investigated through photoluminescence and UV–vis absorption measurements. The polymer displays highly sensitive and selective on-off Hg²⁺ fluorescence quenching property in tetrahydrofuran solution in comparison with the other cations including Mg²⁺, Zn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, and Pb²⁺. More importantly, the fluorescent color of the polymer sensor disappears after addition of Hg²⁺, which could be easily detected by naked eyes. The results indicate that this kind of polymer sensor incorporating benzo[2,1,3]thiadiazole moiety as a ligand can be used as a novel colorimetric and fluorometric sensor for Hg²⁺ detection. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A highly efficient organocatalytic enantioselective CS bond formation reaction between simple alkyl thiols and Morita–Baylis–Hillman (MBH) carbonates is described. The optically active α-methylene β-mercapto esters could be obtained under mild reaction conditions with excellent enantioselectivities (up to 97% ee). The broad scope and simple operation make this methodology very practical.

The highly effective and enantioselective sulfenylation of β-keto phosphonates catalyzed by α,α-diaryl-L-prolinols has been developed. The optically active α-sulfenylated β-keto phosphonates could be obtained under mild reaction conditions in good yields (up to 92%) and with excellent enantioselectivities (up to 92% ee).

A novel imidazolium ion-tagged L-proline catalyst has been developed. The asymmetric α-aminoxylation of aldehydes and ketones with excellent enantioselectivities, up to 99% ee, and high yields in ionic liquids has been achieved. The system can be easily recycled and reused for at least six times without significant loss of yields and enantioselectivity.

A chiral polymer incorporating an (R,R)-salen moiety was synthesized by the polymerization of (R,R)-1,2-diaminocyclohexane with 2,5-dibutoxy-1,4-di(salicyclaldehyde)-1,4-diethynyl-benzene by a nucleophilic addition–elimination reaction. The fluorescence responses of the (R,R)-salen-based polymer toward various metal ions were investigated by fluorescence spectra. Compared with other cations, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, Hg²⁺, and Pb²⁺, Zn²⁺ can lead to a pronounced fluorescence enhancement as high as 7.8-fold together with an obvious blue-shift change of the chiral polymer. More importantly, the fluorescent color of the polymer changed to bright blue instead of weak yellow after addition of Zn²⁺, which can be easily detected by the naked eye. The results indicate that this kind of chiral polymer, incorporating an (R,R)-salen moiety as a receptor in the main chain backbone, can exhibit high sensitivity and selectivity for Zn²⁺ recognition.