Lihua Yuan - Cochemist

Reversibly Tunable Lower Critical Solution Temperature Behavior Induced by H-Bonded Aromatic Amide Macrocycle and Imidazolium Host–Guest Complexation

Co-reporter:Lijun Mao, Wang Pan, Yonghong Fu, Lixi Chen, Min Xu, Yi RenWen Feng, Lihua Yuan

Organic Letters 2017 Volume 19(Issue 1) pp:18-21

Publication Date(Web):December 9, 2016

DOI:10.1021/acs.orglett.6b03125

A new supramolecular host–guest motif comprising an H-bonded aromatic amide macrocycle and imidazolium cation based ionic liquids was developed, which allows tunable binding affinity via altering N-substitution or counterions. This host–guest system exhibits lower critical solution temperature behavior that can be precisely controlled by adjusting concentration, competitive guest, and acid/base. The demonstrated separation of two organic dyes with the supramolecular complex holds promising applications in separation science.

Unusual binding selectivity with non-selective homoditopic pillar[5]arene oxime: serendipitous discovery of a unique approach to heterobinuclear metalation in solution

Co-reporter:Xiangyang Yuan;Yiming Jia;Yimin Cai;Wen Feng;Yiming Li;Xiaopeng Li

Chemical Communications 2017 vol. 53(Issue 19) pp:2838-2841

Publication Date(Web):2017/03/02

DOI:10.1039/C7CC00237H

A heterobinuclear complexation strategy on homoditopic pillar[5]arene was developed by using a pillar[5]arene with two rims decorated with benzaldehyde oximes. The unique selective recognition process was found to result from vesicular formation based on a controllable self-assembly, leading to binding of thorium(IV) only onto one rim, with the other rim being unoccupied for subsequent complexation of a second different metal ion.

Macrocyclic shape-persistency of cyclo[6]aramide results in enhanced multipoint recognition for the highly efficient template-directed synthesis of rotaxanes

Co-reporter:Xiaowei Li;Xiangyang Yuan;Pengchi Deng;Lixi Chen;Yi Ren;Chengyuan Wang;Lixin Wu;Wen Feng;Bing Gong

Chemical Science (2010-Present) 2017 vol. 8(Issue 3) pp:2091-2100

Publication Date(Web):2017/02/28

DOI:10.1039/C6SC04714A

Examples of using two-dimensional shape-persistent macrocycles, i.e. those having noncollapsible and geometrically well-defined skeletons, for constructing mechanically interlocked molecules are scarce, which contrasts the many applications of these macrocycles in molecular recognition and functional self-assembly. Herein, we report the crucial role played by macrocyclic shape-persistency in enhancing multipoint recognition for the highly efficient template-directed synthesis of rotaxanes. Cyclo[6]aramides, with a near-planar conformation, are found to act as powerful hosts that bind bipyridinium salts with high affinities. This unique recognition module, composed of two macrocyclic molecules with one bipyridinium ion thread through the cavity, is observed both in the solid state and in solution, with unusually high binding constants ranging from ∼1013 M−2 to ∼1015 M−2 in acetone. The high efficacy of this recognition motif is embodied by the formation of compact [3]rotaxanes in excellent yields based on either a “click-capping” (91%) or “facile one-pot” (85%) approach, underscoring the great advantage of using H-bonded aromatic amide macrocycles for the highly efficient template-directed synthesis of mechanically interlocked structures. Furthermore, three cyclo[6]aramides bearing different peripheral chains 1–3 demonstrate high specificity in the synthesis of a [3]rotaxane from 1 and 2, and a [2]rotaxane from 3via a “facile one-pot” approach, in each case as the only isolated product. Analysis of the crystal structure of the [3]rotaxane reveals a highly compact binding mode that would be difficult to access using other macrocycles with a flexible backbone. Leveraging this unique recognition motif, resulting from the shape-persistency of these oligoamide macrocycles, in the template-directed synthesis of compact rotaxanes may open up new opportunities for the development of higher order interlocked molecules and artificial molecular machines.

A Redox-Responsive Complex System Based on 2D Shape-Persistent Cyclo[6]aramide and Ferrocenium

Co-reporter:Long Chen;Xiangyang Yuan;Zixiao Wang;Youran Luo;Wei Huang;Shuai Zhang;Wenli Yuan; Song Qin; Guohong Tao ; Lihua Yuan

Asian Journal of Organic Chemistry 2016 Volume 5( Issue 8) pp:966-970

Publication Date(Web):

DOI:10.1002/ajoc.201600161

Abstract

Electrochemical stimuli-responsive systems via macrocyclic host–guest interactions are of practical significance in realizing functions of biological materials and synthetic molecular machines. In this study, a cyclo[6]aramide-ferrocenium (Fc⁺) recognition motif was demonstrated to be a novel redox-responsive system based on two-dimensional (2D) macrocycle in organic media, in which the host strongly binds the oxidized form Fc⁺ and shows no complexation towards the reduced form ferrocene. Results from cyclic voltammetric experiments clearly show the redox responsiveness of the claimed system, in sharp contrast to a control system based on an acyclic compound that contains the same number of introverted amide oxygens, highlighting the importance of the macrocyclic effect in the redox process. This study provides a rare example of using 2D hydrogen-bonded aromatic amide macrocycles to form a ferrocene-based redox-responsive inclusion complex and thus paves the way for future applications.

Ion-pair recognition of amidinium salts by partially hydrogen-bonded heteroditopic cyclo[6]aramide

Co-reporter:Shanshan Shi, Yumin Zhu, Xiaowei Li, Xiangyang Yuan, Teng Ma, Wen-Li Yuan, Guo-Hong Tao, Wen Feng and Lihua Yuan

RSC Advances 2016 vol. 6(Issue 46) pp:39839-39845

Publication Date(Web):14 Apr 2016

DOI:10.1039/C6RA08202E

Convergent heteroditopic cyclo[6]aramide demonstrates efficient ion-pair recognition of amidinium salts in 10% methanolic chloroform (>104 M−1) as confirmed by NMR and conductivity experiments. As predicted by density functional theory (DFT) method simulations, cyclo[6]aramide 1a is able to bind amidinium salts G1–G5 with varying binding affinity in 1:1 stoichiometry through hydrogen bonding interactions involving both anion-recognizing amide H-atoms and cation-binding amide carbonyl O-atoms. Particularly, the binding affinities for G1, G2 and G3 are found to decrease with increasing the size of substituents in the amidinium ion in the order of G1 > G2 > G3. Moreover, the association ability for simultaneous binding of cationic and anionic guest species depends considerably on the counterions. Among the four formamidinium salts (Cl−, Br−, I− and BPh4−) examined, formamidinium chloride is best encapsulated as a contact ion-pair species in the macrocycle. The reduced association constants with increasing the size of counterions in the order of G1 > G6 > G7 > G4 underscore the importance of ion paring in effecting the host–guest interaction. Comparative conductivity studies provide a convenient approach to differentiate between contact and loose ion pairs for these amidinium complexes. This work provides a rare example of binding biologically important types of amidinium cations as ion pairs by a synthetic receptor.

Ditopic CMPO-pillar[5]arenes as unique receptors for efficient separation of americium(III) and europium(III)

Co-reporter:Yuyu Fang, Xiangyang Yuan, Lei Wu, Zhiyong Peng, Wen Feng, Ning Liu, Dingguo Xu, Shoujian Li, Arijit Sengupta, Prasanta K. Mohapatra and Lihua Yuan

Chemical Communications 2015 vol. 51(Issue 20) pp:4263-4266

Publication Date(Web):27 Jan 2015

DOI:10.1039/C4CC09248A

A unique host–guest recognition process involving a new class of homoditopic CMPO-pillar[5]arenes and lanthanides was revealed to proceed in a stepwise manner, and correlated with the efficient separation of americium(III) and europium(III) under acidic feed conditions.

Cyclo[6]aramide-Tropylium Charge Transfer Complex as a Colorimetric Chemosensor for Differentiation of Intimate and Loose Ion Pairs

Co-reporter:Long Chen, Zhiyong Peng, Shuo Liu, Xiaowei Li, Rongzhou Chen, Yi Ren, Wen Feng, and Lihua Yuan

Organic Letters 2015 Volume 17(Issue 24) pp:5950-5953

Publication Date(Web):November 30, 2015

DOI:10.1021/acs.orglett.5b02829

Shape-persistent iso-C16-cyclo[6]aramide (1) was found to form a charge-transfer (CT) complex with aromatic carbonium tropylium (Tr+). The resulting CT complex was evidenced by both experimental results and theoretical calculations. Particularly, dibutylammonium salt with PF6– as the counterion can extrude Tr+ from the CT complex, but it cannot do so with Cl–, thereby offering a visual approach to identify organic intimate ion pairs and loose ion pairs.

A non-symmetric pillar[5]arene based on triazole-linked 8-oxyquinolines as a sequential sensor for thorium(IV) followed by fluoride ions

Co-reporter:Yuyu Fang, Caixia Li, Lei Wu, Bing Bai, Xing Li, Yiming Jia, Wen Feng and Lihua Yuan

Dalton Transactions 2015 vol. 44(Issue 33) pp:14584-14588

Publication Date(Web):05 Feb 2015

DOI:10.1039/C5DT00089K

A novel non-symmetric pillar[5]arene bearing triazole-linked 8-oxyquinolines at one rim was synthesized and demonstrated as a sequential fluorescence sensor for thorium(IV) followed by fluoride ions with high sensitivity and selectivity.

Convergent heteroditopic cyclo[6]aramides as macrocyclic ion-pair receptors for constructing [2]pseudorotaxanes

Co-reporter:Jinchuan Hu, Long Chen, Jie Shen, Jian Luo, Pengchi Deng, Yi Ren, Huaqiang Zeng, Wen Feng and Lihua Yuan

Chemical Communications 2014 vol. 50(Issue 59) pp:8024-8027

Publication Date(Web):30 Apr 2014

DOI:10.1039/C4CC02557A

A strategy of using amide groups as the only functionality was developed to construct convergent heteroditopic cyclo[6]aramides that are able to strongly bind dibutylammonium chloride in chloroform (>105 M−1), leading to the formation of [2]pseudorotaxanes.

Pillar[5]arene-based diglycolamides for highly efficient separation of americium(III) and europium(III)

Co-reporter:Lei Wu, Yuyu Fang, Yiming Jia, Yuanyou Yang, Jiali Liao, Ning Liu, Xinshi Yang, Wen Feng, Jialin Ming and Lihua Yuan

Dalton Transactions 2014 vol. 43(Issue 10) pp:3835-3838

Publication Date(Web):23 Dec 2013

DOI:10.1039/C3DT53336K

Pillar[5]arenes, as a new intriguing class of calixarene analogues, were functionalized with ten diglycolamide (DGA) arms on both sides (rims) of the pillar framework and evaluated for their extraction behaviour towards Am(III) and Eu(III). These novel extractants exhibit excellent separation and extraction efficiency, suggesting its significant potential for nuclear waste remediation. Laser induced fluorescence experiments disclosed strong complexation of the trivalent metal ions with the pillararene-DGA ligands.

An insight into the extraction of transition metal ions by picolinamides associated with intramolecular hydrogen bonding and rotational isomerization

Co-reporter:Yan Li, Yiming Jia, Zhenwen Wang, Xianghui Li, Wen Feng, Pengchi Deng and Lihua Yuan

RSC Advances 2014 vol. 4(Issue 56) pp:29702-29714

Publication Date(Web):19 Jun 2014

DOI:10.1039/C4RA02030H

The clear connection between molecular structures of N-substituted picolinamides and extraction behaviour has been rationalized by highlighting the relationship between intramolecular hydrogen bonding and rotational isomerism. To this aim aromatic pyridine-2,6-dicarboxamides 1a–1c with N-substitution and their analogues 3a and 3b containing intramolecular hydrogen bonds were designed and synthesized. The results from the liquid–liquid extraction towards some representative transition metal picrates including Ag+, Hg2+, Pb2+, Cd2+, Zn2+, Cu2+, Co2+ and Ni2+ salts demonstrated that the higher selectivity and efficiency towards Hg2+ (88.6–95.4%) over other metal cations stem mainly from N-substitution via disruption of intramolecular H-bonding. X-ray structural analysis, and ordinary and variable-temperature proton and carbon NMR experiments provided supporting information for expounding the difference in extraction ability among these ligands, particularly the importance of N-substitution that leads to the formation of rotamers affecting the extraction process.

Pillar[5]arenes bearing phosphine oxide pendents as Hg2+ selective receptors

Co-reporter:Yiming Jia, Yuyu Fang, Yan Li, Lutao He, Wenhua Fan, Wen Feng, Yuanyou Yang, Jiali Liao, Ning Liu, Lihua Yuan

Talanta 2014 Volume 125() pp:322-328

Publication Date(Web):1 July 2014

DOI:10.1016/j.talanta.2014.03.006

•Pillar[5]arene-based phoshpine oxides were first used as mercury receptors.•High efficiency and superior selectivity for Hg2+ were achieved in solvent extraction.•The binding mode between the receptors and mercury was revealed by UV–vis and NMR experiments.•The receptors were successfully applied for separating and detecting Hg2+ in real water samples.Pillar[5]arenes bearing ten phosphine oxide groups (1a–e), as analogs of their corresponding calix[4]arene-based phosphine oxide, have demonstrated intriguing recognition performance for some representative heavy metal cations including Co2+, Cu2+, Ni2+, Zn2+, Cd2+, Pb2+, Ag2+ and Hg2+ compared to their acyclic species (2a–e). Their extraction abilities toward these cations were evaluated by the solvent extraction method. The extraction results revealed that 1a–e were efficient and selective cation receptors for Hg2+ over other selected cations. In addition, the complexation behavior of 1a–e for Hg2+ was also investigated by using NMR and UV–vis techniques. The pillarareen receptors have been first used in the determination of inorganic mercury in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES), after back-extracting into aqueous phase with 3 mol L−1 HCl and 1% CS(NH2)2 solution.

A novel strategy for making poly(vinyl alcohol)/reduced graphite oxide nanocomposites by solvothermal reduction

Co-reporter:Jingjing Li, Leishan Shao, Lihua Yuan, Yinghan Wang

Materials & Design 2014 54() pp: 520-525

Publication Date(Web):February 2014

DOI:10.1016/j.matdes.2013.08.090

•A new strategy was proposed to make PVA/rGO composites by solvothermal reduction.•The solvent acted not only as a reducing agent but also as a good stabilizer.•The homogeneous dispersion of rGO sheets in the PVA matrix was achieved.•The crystallinity of PVA/rGO nanocomposites was investigated.•Mechanical properties and thermal stability were greatly improved by adding rGO.Poly(vinyl alcohol) (PVA)/reduced graphite oxide (rGO) nanocomposites were synthesized by solvothermal reduction of graphite oxide (GO) in the presence of PVA. The solvent, the mixed dimethyl sulfoxide (DMSO)-dimethylformamide (DMF), could act not only as a reducing agent but also as a good stabilizer, which achieved effectively reduction of GO in the PVA matrix and avoided the agglomeration of rGO during reduction. A 53.0% increase in tensile strength and 52.6% improvement of Young’s modulus were achieved by addition of 3 wt% of rGO. Furthermore, a significant improvement of thermal stability was observed for the PVA/rGO nanocomposites.

Two-Component Supramolecular Gels Derived from Amphiphilic Shape-Persistent Cyclo[6]aramides for Specific Recognition of Native Arginine

Co-reporter:Youzhou He;Min Xu;Rongzhao Gao;Xiaowei Li;Fengxue Li;Xuedan Wu; Dingguo Xu;Dr. Huaqiang Zeng; Lihua Yuan

Angewandte Chemie International Edition 2014 Volume 53( Issue 44) pp:11834-11839

Publication Date(Web):

DOI:10.1002/anie.201407092

Abstract

A unique supramolecular two-component gelation system was constructed from amphiphilic shape-persistent cyclo[6]aramides and diethylammonium chloride (or triethylammonium chloride). This system has the ability to discriminate native arginine from 19 other amino acids in a specific fashion. Cyclo[6]aramides show preferential binding for the guanidinium residue over ammonium groups. This specificity was confirmed by both experimental results and theoretical simulations. These results demonstrated a new modular displacement strategy, exploring the use of species-binding hydrogen-bonded macrocyclic foldamers for the construction of two-component gelation systems for selective recognition of native amino acids by competitive host–guest interactions. This strategy may be amenable to developing a variety of functional two-component gelators for specific recognition of various targeted organic molecular species.

Two-Component Supramolecular Gels Derived from Amphiphilic Shape-Persistent Cyclo[6]aramides for Specific Recognition of Native Arginine

Co-reporter:Youzhou He;Min Xu;Rongzhao Gao;Xiaowei Li;Fengxue Li;Xuedan Wu; Dingguo Xu;Dr. Huaqiang Zeng; Lihua Yuan

Angewandte Chemie 2014 Volume 126( Issue 44) pp:12028-12033

Publication Date(Web):

DOI:10.1002/ange.201407092

Abstract

A unique supramolecular two-component gelation system was constructed from amphiphilic shape-persistent cyclo[6]aramides and diethylammonium chloride (or triethylammonium chloride). This system has the ability to discriminate native arginine from 19 other amino acids in a specific fashion. Cyclo[6]aramides show preferential binding for the guanidinium residue over ammonium groups. This specificity was confirmed by both experimental results and theoretical simulations. These results demonstrated a new modular displacement strategy, exploring the use of species-binding hydrogen-bonded macrocyclic foldamers for the construction of two-component gelation systems for selective recognition of native amino acids by competitive host–guest interactions. This strategy may be amenable to developing a variety of functional two-component gelators for specific recognition of various targeted organic molecular species.

Nonaggregational Shape-Persistent Cyclo[6]aramide and Its Macrocyclic Effect toward Binding Secondary Ammonium Salts in Moderately Polar Media

Co-reporter:Jinchuan Hu, Long Chen, Yi Ren, Pengchi Deng, Xiaowei Li, Youjia Wang, Yiming Jia, Jian Luo, Xinshi Yang, Wen Feng, and Lihua Yuan

Organic Letters 2013 Volume 15(Issue 18) pp:4670-4673

Publication Date(Web):September 11, 2013

DOI:10.1021/ol401930u

Simply by introducing steric side chains, the shape-persistent cyclo[6]aramides were found to exhibit nonaggregational behavior and strong association (3 × 104 M–1) ability in acetone for binding secondary ammonium salt. The complexation can be switched in an on-and-off fashion using AgPF6 and TBACl, contrasting sharply with their corresponding acyclic pentamer and demonstrating the macrocyclic effect.

Single-molecule observation of the K+-induced switching of valinomycin within a template network

Co-reporter:Yibao Li, Chunhua Liu, Yunzhi Xie, Xun Li, Xiaolin Fan, Lihua Yuan and Qingdao Zeng

Chemical Communications 2013 vol. 49(Issue 79) pp:9021-9023

Publication Date(Web):09 Aug 2013

DOI:10.1039/C3CC44978E

The K+-induced switching of valinomycin has been studied using a molecular template formed by an aromatic oligoamide macrocycle at the liquid/solid interface by scanning tunneling microscopy (STM). Individual valinomycin and its K+ complex can be identified and resolved in the molecular template, and the high-resolution STM images of valinomycin and its K+ complex show triangle-like and cyclic structural characteristics, respectively.

Quadruply hydrogen-bonded heteroduplexes based on imide and urea units arrayed with ADDA/DAAD sequences

Co-reporter:Xianghui Li, Yiming Jia, Yi Ren, Youjia Wang, Jinchuan Hu, Teng Ma, Wen Feng and Lihua Yuan

Organic & Biomolecular Chemistry 2013 vol. 11(Issue 40) pp:6975-6983

Publication Date(Web):20 Aug 2013

DOI:10.1039/C3OB40998H

A new class of imide- and urea-based hetero-strands with a quadruple ADDA/DAAD hydrogen-bond array was designed and synthesized from easily accessible starting materials. The molecular recognition between the two different strands depends highly on the substituents and the linker between neighboring hydrogen-bonds, which results in the stability of these heteroduplexes varying from 103 to >105 M−1 in apolar solvents. In particular, an increase of the association constant by up to one order of magnitude was observed by derivatizing the ADDA arrays at the termini with electron-withdrawing groups. Molecular modelling of the representative complementary complexes reveals the binding mode of four hydrogen-bond arrays that agrees with the matched pair.

Pillar[5]arene-based phosphine oxides: novel ionophores for solvent extraction separation of f-block elements from acidic media

Co-reporter:Yuyu Fang, Lei Wu, Jiali Liao, Long Chen, Yuanyou Yang, Ning Liu, Lutao He, Shuliang Zou, Wen Feng and Lihua Yuan

RSC Advances 2013 vol. 3(Issue 30) pp:12376-12383

Publication Date(Web):01 May 2013

DOI:10.1039/C3RA41251B

A new class of pillar[5]arene-based phosphine oxides tethered with ten chelating groups on both rims of the pillar were synthesized via two steps from macrocyclization of 1,4-bis(bromoalkoxy)benzenes with paraformaldehyde, followed by Arbusov reaction with iso-propoxydiphenylphosphine. Solvent extraction of these ligands towards selected lanthanides and actinides was investigated under acidic condition. Compared with acyclic monovalent analogs and classical extractant tri-n-octylphosphine oxide (TOPO), the remarkable efficiency and selectivity for thorium(IV) and uranyl(VI) as observed in these novel extractants bearing a varying spacer length revealed the significance of preorganization of chelating groups on pillararene platform. Log–log plot analysis indicated the 1:1 stoichiometry (ligand/metal) for the extracted complex formed between the ligand and thorium(IV) or uranyl(VI). The extraction efficiency was considerably improved with increasing acidity in a range of 0.1–1.5 M HNO3, a result that is distinct from the extraction behaviour of calixarene-based phosphine oxides. The extractability increased with enhancing NaNO3 concentration and high salinity assisted the preferential extraction of U(VI) over Th(IV). These ligands also showed moderate efficiency in differentiating europium(III) and americium(III) at 1 M HNO3 in the presence of a synergist (Br6-COSAN).

Tunable Mesogens Based on Shape-Persistent Aromatic Oligoamides: From Lamellar, Columnar, to Nematic Liquid Crystalline Phase

Co-reporter:Shuliang Zou, Lutao He, Jing Zhang, Youzhou He, Lihua Yuan, Lixin Wu, Jian Luo, Yinghan Wang, and Wen Feng

Organic Letters 2012 Volume 14(Issue 14) pp:3584-3587

Publication Date(Web):June 29, 2012

DOI:10.1021/ol301057g

Crescent aromatic oligoamides are shown to form thermotropic lamellar columnar, rectangular columnar, and discotic nematic mesophases according to structural variation, demonstrating their capability to serve as a new class of diverse mesogens of liquid crystals.

Supramolecular graft copolymers in moderately polar media based on hydrogen-bonded aromatic oligoamide units

Co-reporter:Xusong Pan, Chao Chen, Jiang Peng, Yongan Yang, Yinghan Wang, Wen Feng, Pengchi Deng and Lihua Yuan

Chemical Communications 2012 vol. 48(Issue 76) pp:9510-9512

Publication Date(Web):02 Aug 2012

DOI:10.1039/C2CC35004A

By exploiting hetero-complementary aromatic oligoamide units containing hextuple hydrogen bonds, supramolecular graft copolymers were successfully constructed in moderately polar media.

Shape-persistent macrocycles: efficient extraction towards lanthanide and actinide elements

Co-reporter:Lijian Zhong;Long Chen;Wen Feng

Journal of Inclusion Phenomena and Macrocyclic Chemistry 2012 Volume 72( Issue 3-4) pp:367-373

Publication Date(Web):2012 April

DOI:10.1007/s10847-011-9991-9

The extraction of three shape-persistent aromatic oligoamide macrocycles (cycloaramides) bearing either apolar or polar side chains at the periphery of the rings has been investigated towards some representative lanthanide and actinide ions, and alkali metal ions. The results from the liquid–liquid extraction of lanthanide and thorium ions from aqueous solutions into dichloromethane revealed remarkably high extractability of up to 99% and selectivity over alkali metal cations. The stoichiometry of the complex formed between the macrocycle and Eu3+ or Th4+ was determined to be 1:1.

Strong Aggregation and Directional Assembly of Aromatic Oligoamide Macrocycles

Co-reporter:Yongan Yang ; Wen Feng ; Jinchuan Hu ; Shuliang Zou ; Rongzhao Gao ; Kazuhiro Yamato ; Mark Kline ; Zhonghou Cai ; Yi Gao ; Yibing Wang ; Yibao Li ; Yanlian Yang ; Lihua Yuan ; Xiao Cheng Zeng ;Bing Gong

Journal of the American Chemical Society 2011 Volume 133(Issue 46) pp:18590-18593

Publication Date(Web):October 24, 2011

DOI:10.1021/ja208548b

Aromatic oligoamide macrocycles exhibit strong preference for highly directional association. Aggregation happens in both nonpolar and polar solvents but is weakened as solvent polarity increases. The strong, directional assembly is rationalized by the cooperative action of dipole–dipole and π–π stacking interactions, leading to long nanotubular assemblies that are confirmed by SEM, TEM, AFM, and XRD. The persistent nanotubular assemblies contain non-collapsible hydrophilic internal pores that mediate highly efficient ion transport observed with these macrocycles and serve as cylindrical sites for accommodating guests such as metal ions.

Alternative Strategy for Adjusting the Association Specificity of Hydrogen-Bonded Duplexes

Co-reporter:Penghui Zhang, Hongzhu Chu, Xianghui Li, Wen Feng, Pengchi Deng, Lihua Yuan, and Bing Gong

Organic Letters 2011 Volume 13(Issue 1) pp:54-57

Publication Date(Web):December 6, 2010

DOI:10.1021/ol102522m

A strategy for creating new association specificity of hydrogen-bonded duplexes by varying the spacings between neighboring hydrogen bonds is described. Incorporation of naphthalene-based residues has provided oligoamide strands that pair into duplexes sharing the same H-bonding sequences (e.g., DDAA) but differing in the spacings between their intermolecular hydrogen bonds, leading to homo- or heteroduplexes. The ability to manipulate association-specificity as demonstrated by this work may be extended to other multiple hydrogen bonded systems, thereby further enhancing the diversity of multiple hydrogen-bonded association units for constructing supramolecular structures.

Self-Complementary Quadruply Hydrogen-Bonded Duplexes Based on Imide and Urea Units

Co-reporter:Xianghui Li, Yuyu Fang, Pengchi Deng, Jinchuan Hu, Tian Li, Wen Feng, and Lihua Yuan

Organic Letters 2011 Volume 13(Issue 17) pp:4628-4631

Publication Date(Web):August 5, 2011

DOI:10.1021/ol2018455

The quadruply hydrogen-bonded duplexes based on an imide-urea structure preorganized by three-center hydrogen bonds were found to associate via bifurcated hydrogen bonds. 1H NMR dilution experiments revealed the high stability of the homodimer in apolar solvent (Kdim > 105 M–1 in CDCl3) and enhancement of association ability due to electron-withdrawing substituent effects. The ready synthetic availability and adjustable association affinity via electronic effects may render these association units potentially applicable in constructing supramolecular architectures.

Oligoamide Duplexes as Organogelators

Co-reporter:Ruikai Cao, Jingjing Zhou, Wei Wang, Wen Feng, Xianghui Li, Penghui Zhang, Pengchi Deng, Lihua Yuan and Bing Gong

Organic Letters 2010 Volume 12(Issue 13) pp:2958-2961

Publication Date(Web):June 10, 2010

DOI:10.1021/ol100953e

Oligoamide duplexes carrying multiple alkyl side chains were found to serve as gelators for aromatic solvents. The double-stranded backbone was essential for the hierarchical self-assembly of the molecular duplex into fibers of high aspect ratios. The demonstrated gelating abilities may be extended to a large family of analogous H-bonded duplexes having different H-bonding sequences, leading to a unique platform for developing a diverse variety of potential gelators based on a supramolecular and/or a dynamic covalent approach.

Macrocyclic shape-persistency of cyclo[6]aramide results in enhanced multipoint recognition for the highly efficient template-directed synthesis of rotaxanes

Co-reporter:Xiaowei Li, Xiangyang Yuan, Pengchi Deng, Lixi Chen, Yi Ren, Chengyuan Wang, Lixin Wu, Wen Feng, Bing Gong and Lihua Yuan

Chemical Science (2010-Present) 2017 - vol. 8(Issue 3) pp:NaN2100-2100

Publication Date(Web):2016/11/22

DOI:10.1039/C6SC04714A

Examples of using two-dimensional shape-persistent macrocycles, i.e. those having noncollapsible and geometrically well-defined skeletons, for constructing mechanically interlocked molecules are scarce, which contrasts the many applications of these macrocycles in molecular recognition and functional self-assembly. Herein, we report the crucial role played by macrocyclic shape-persistency in enhancing multipoint recognition for the highly efficient template-directed synthesis of rotaxanes. Cyclo[6]aramides, with a near-planar conformation, are found to act as powerful hosts that bind bipyridinium salts with high affinities. This unique recognition module, composed of two macrocyclic molecules with one bipyridinium ion thread through the cavity, is observed both in the solid state and in solution, with unusually high binding constants ranging from ∼1013 M−2 to ∼1015 M−2 in acetone. The high efficacy of this recognition motif is embodied by the formation of compact [3]rotaxanes in excellent yields based on either a “click-capping” (91%) or “facile one-pot” (85%) approach, underscoring the great advantage of using H-bonded aromatic amide macrocycles for the highly efficient template-directed synthesis of mechanically interlocked structures. Furthermore, three cyclo[6]aramides bearing different peripheral chains 1–3 demonstrate high specificity in the synthesis of a [3]rotaxane from 1 and 2, and a [2]rotaxane from 3via a “facile one-pot” approach, in each case as the only isolated product. Analysis of the crystal structure of the [3]rotaxane reveals a highly compact binding mode that would be difficult to access using other macrocycles with a flexible backbone. Leveraging this unique recognition motif, resulting from the shape-persistency of these oligoamide macrocycles, in the template-directed synthesis of compact rotaxanes may open up new opportunities for the development of higher order interlocked molecules and artificial molecular machines.

Convergent heteroditopic cyclo[6]aramides as macrocyclic ion-pair receptors for constructing [2]pseudorotaxanes

Co-reporter:Jinchuan Hu, Long Chen, Jie Shen, Jian Luo, Pengchi Deng, Yi Ren, Huaqiang Zeng, Wen Feng and Lihua Yuan

Chemical Communications 2014 - vol. 50(Issue 59) pp:NaN8027-8027

Publication Date(Web):2014/04/30

DOI:10.1039/C4CC02557A

A strategy of using amide groups as the only functionality was developed to construct convergent heteroditopic cyclo[6]aramides that are able to strongly bind dibutylammonium chloride in chloroform (>105 M−1), leading to the formation of [2]pseudorotaxanes.

A non-symmetric pillar[5]arene based on triazole-linked 8-oxyquinolines as a sequential sensor for thorium(IV) followed by fluoride ions

Co-reporter:Yuyu Fang, Caixia Li, Lei Wu, Bing Bai, Xing Li, Yiming Jia, Wen Feng and Lihua Yuan

Dalton Transactions 2015 - vol. 44(Issue 33) pp:NaN14588-14588

Publication Date(Web):2015/02/05

DOI:10.1039/C5DT00089K

A novel non-symmetric pillar[5]arene bearing triazole-linked 8-oxyquinolines at one rim was synthesized and demonstrated as a sequential fluorescence sensor for thorium(IV) followed by fluoride ions with high sensitivity and selectivity.

Pillar[5]arene-based diglycolamides for highly efficient separation of americium(III) and europium(III)

Co-reporter:Lei Wu, Yuyu Fang, Yiming Jia, Yuanyou Yang, Jiali Liao, Ning Liu, Xinshi Yang, Wen Feng, Jialin Ming and Lihua Yuan

Dalton Transactions 2014 - vol. 43(Issue 10) pp:NaN3838-3838

Publication Date(Web):2013/12/23

DOI:10.1039/C3DT53336K

Pillar[5]arenes, as a new intriguing class of calixarene analogues, were functionalized with ten diglycolamide (DGA) arms on both sides (rims) of the pillar framework and evaluated for their extraction behaviour towards Am(III) and Eu(III). These novel extractants exhibit excellent separation and extraction efficiency, suggesting its significant potential for nuclear waste remediation. Laser induced fluorescence experiments disclosed strong complexation of the trivalent metal ions with the pillararene-DGA ligands.

Ditopic CMPO-pillar[5]arenes as unique receptors for efficient separation of americium(III) and europium(III)

Co-reporter:Yuyu Fang, Xiangyang Yuan, Lei Wu, Zhiyong Peng, Wen Feng, Ning Liu, Dingguo Xu, Shoujian Li, Arijit Sengupta, Prasanta K. Mohapatra and Lihua Yuan

Chemical Communications 2015 - vol. 51(Issue 20) pp:NaN4266-4266

Publication Date(Web):2015/01/27

DOI:10.1039/C4CC09248A

A unique host–guest recognition process involving a new class of homoditopic CMPO-pillar[5]arenes and lanthanides was revealed to proceed in a stepwise manner, and correlated with the efficient separation of americium(III) and europium(III) under acidic feed conditions.

Supramolecular graft copolymers in moderately polar media based on hydrogen-bonded aromatic oligoamide units

Co-reporter:Xusong Pan, Chao Chen, Jiang Peng, Yongan Yang, Yinghan Wang, Wen Feng, Pengchi Deng and Lihua Yuan

Chemical Communications 2012 - vol. 48(Issue 76) pp:NaN9512-9512

Publication Date(Web):2012/08/02

DOI:10.1039/C2CC35004A

By exploiting hetero-complementary aromatic oligoamide units containing hextuple hydrogen bonds, supramolecular graft copolymers were successfully constructed in moderately polar media.

Quadruply hydrogen-bonded heteroduplexes based on imide and urea units arrayed with ADDA/DAAD sequences

Co-reporter:Xianghui Li, Yiming Jia, Yi Ren, Youjia Wang, Jinchuan Hu, Teng Ma, Wen Feng and Lihua Yuan

Organic & Biomolecular Chemistry 2013 - vol. 11(Issue 40) pp:NaN6983-6983

Publication Date(Web):2013/08/20

DOI:10.1039/C3OB40998H

A new class of imide- and urea-based hetero-strands with a quadruple ADDA/DAAD hydrogen-bond array was designed and synthesized from easily accessible starting materials. The molecular recognition between the two different strands depends highly on the substituents and the linker between neighboring hydrogen-bonds, which results in the stability of these heteroduplexes varying from 103 to >105 M−1 in apolar solvents. In particular, an increase of the association constant by up to one order of magnitude was observed by derivatizing the ADDA arrays at the termini with electron-withdrawing groups. Molecular modelling of the representative complementary complexes reveals the binding mode of four hydrogen-bond arrays that agrees with the matched pair.

Single-molecule observation of the K+-induced switching of valinomycin within a template network

Co-reporter:Yibao Li, Chunhua Liu, Yunzhi Xie, Xun Li, Xiaolin Fan, Lihua Yuan and Qingdao Zeng

Chemical Communications 2013 - vol. 49(Issue 79) pp:NaN9023-9023

Publication Date(Web):2013/08/09

DOI:10.1039/C3CC44978E

The K+-induced switching of valinomycin has been studied using a molecular template formed by an aromatic oligoamide macrocycle at the liquid/solid interface by scanning tunneling microscopy (STM). Individual valinomycin and its K+ complex can be identified and resolved in the molecular template, and the high-resolution STM images of valinomycin and its K+ complex show triangle-like and cyclic structural characteristics, respectively.

Unusual binding selectivity with non-selective homoditopic pillar[5]arene oxime: serendipitous discovery of a unique approach to heterobinuclear metalation in solution

Co-reporter:Xiangyang Yuan, Yiming Jia, Yimin Cai, Wen Feng, Yiming Li, Xiaopeng Li and Lihua Yuan

Chemical Communications 2017 - vol. 53(Issue 19) pp:NaN2841-2841

Publication Date(Web):2017/02/10

DOI:10.1039/C7CC00237H

A heterobinuclear complexation strategy on homoditopic pillar[5]arene was developed by using a pillar[5]arene with two rims decorated with benzaldehyde oximes. The unique selective recognition process was found to result from vesicular formation based on a controllable self-assembly, leading to binding of thorium(IV) only onto one rim, with the other rim being unoccupied for subsequent complexation of a second different metal ion.