Total spontaneous resolution of chiral covalent networks from stereochemically labile metal complexes

Stereochemically labile copper and zinc complexes with the N,N'-dimethylethylenediamine ligand (dmeda) have been shown to be promising precursors for the total spontaneous resolution of chiral covalent networks. (N,N')-[Cu(NO3)2(dmeda)]infinity crystallises as a conglomerate and yields either enantiopure (R,R)-1 or enantiopure (S,S)-1. A mixed-valence copper(I/II) complex, [{Cu(II)Br2(dmeda)}3(Cu(I)Br)2]infinity (2), which crystallises as a pair of interpenetrating chiral (10,3)-a nets, is formed from CuBr, CuBr2 and dmeda. One net contains ligands with solely (R,R) configuration and exhibits helices with (P) configuration while the other has solely (S,S)-dmeda ligands and gives rise to a net in which the helices have (M) configuration. The whole crystalline arrangement is racemic, because the interpenetrating chiral nets are of opposite handedness. With zinc chloride (R,S)-[ZnCl(dmeda)2]2[ZnCl4] (3) is obtained, which is a network structure, although not chiral. Total spontaneous resolution of stereochemically labile metal complexes formed from achiral or racemic building blocks is suggested as a viable route for the preparation of covalent chiral networks. Once the absolute structure of the compound has been determined by X-ray crystallography, a quantitative determination of the enantiomeric excess of the bulk product can be undertaken by means of solid-state CD spectroscopy.     

Two cadmium compounds with adenine and carboxylate ligands: syntheses,structures and photoluminescence

Two cadmium(II) coordination compounds, [Cd₃(CH₃CO₂)₄(ad)₂(CH₃CN)₂]_n (1) and [Cd₃(5-SIP)₂(H-ad)₂(H₂O)₆]_n (2) (H-ad = adenine and 5-SIP = 5-sulfoisophthalate), were synthesized and characterized. Compound 1 features a two-dimensional (2-D) layered structure based on linear trinuclear [Cd₃(CH₃CO₂)₄] units bridged by monoanionic adenine ligands. In 2, the 5-SIP^3? ligands link Cd(II) ions to form a one-dimensional (1-D) ladder, which is further linked by neutral adenine ligands to give a 2-D layered structure. In both structures, the carboxylate ligands link Cd(II) ions to form low-dimensional structures, which are further connected by adenine ligands to give high-dimensional structures. Compounds 1 and 2 exhibit emissions centered at 382 and 416 nm, respectively, which can be attributed to the ligand centered π–π* transition.     

Poly(p‐benzamide) having isopropyl‐substituted chiral tri(ethylene glycol) side Chain: Synthesis and helical conformation

Isopropyl‐substituted tri(ethylene glycol) is used as a chiral side chain of N‐substituted poly(p‐benzamide) in order to increase the difference of stability between the right‐ and left‐handed helical structures of the polymer. The target polymer is synthesized by the chain‐growth condensation polymerization of the corresponding monomer with an initiator using lithium 1,1,1,3,3,3‐hexamethyldisilazide as a base. A circular dichroism (CD) study of the polymer reveals that the CD signal is due to an excess of a thermodynamically controlled right‐handed helical structure of the polymer, and that the replacement of the methyl group with a bulkier isopropyl group at the side chain of poly(p‐benzamide) increases the abundance of right‐handed helical structure in chloroform. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1623–1628     

不同V型辅助配体构筑的两个镉配位聚合物的合成、结构和荧光性质

在溶剂热条件下，合成了 2 个基于 V 型辅助配体(bipmo、bppmo)的镉配位聚合物{[Cd(bipmo)(NDC)]·1.75H₂O}_n (1)和{[Cd(bppmo)(NDC)(H₂O)]·H₂O}_n (2)，其中 H2NDC=2，6 萘二羧酸，bipmo=双(4 (1H 咪唑 1 基)苯基)甲酮，bppmo=双(4 (吡啶 4 基)苯基)甲酮。利用单晶X射线衍射、键价和分析、红外光谱和元素分析对其结构进行了表征。研究发现，配合物1具有二重互穿的{63}拓扑结构。配合物2同样是 3 连接的{6³}拓扑，却存在三重穿插结构。分析表明，V型配体对最终结构的形成有很大影响。此外，对配合物1和2的发光性质也进行了详细研究。     

不同V型辅助配体构筑的两个镉配位聚合物的合成、结构和荧光性质

在溶剂热条件下,合成了2个基于V型辅助配体（bipmo、bppmo）的镉配位聚合物{[Cd （bipmo）（NDC）]·1.75H₂O}_n（1）和{[Cd （bppmo）（NDC）（H₂O）]·H₂O}_n（2）,其中H₂NDC=2,6-萘二羧酸,bipmo=双（4-（1H-咪唑-1-基）苯基）甲酮,bppmo=双（4-（吡啶-4-基）苯基）甲酮。利用单晶X射线衍射、键价和分析、红外光谱和元素分析对其结构进行了表征。研究发现,配合物1具有二重互穿的{6³}拓扑结构。配合物2同样是3-连接的{6³}拓扑,却存在三重穿插结构。分析表明,V型配体对最终结构的形成有很大影响。此外,对配合物1和2的发光性质也进行了详细研究。     

Designed synthesis and chiroptical properties of regioregular poly(p-phenyleneethynylene-alter-m-phenyleneethynylene) bearing (−)-trans-myrtanoxyl side groups

Two regioregular poly(p-phenyleneethynylene-alter-m-phenyleneethynylene)s bearing (−)-trans-myrtanoxyl side groups with different substitution patterns were designed and synthesized, e.g. Myr-PMPE-1 and Myr-PMPE-2. In Myr-PMPE-1, the side chiral groups are distributed uniformly along the backbone. In Myr-PMPE-2, the distribution of the side chiral groups is alternatively crowded and loose. Both of these two polymers show no CD signal in solutions because of their good solubility. The investigations of chiroptical properties of these two polymers were carried out in the form of spin-coated films. The films were annealed above the glass temperature of the corresponding polymer, and the effects of annealing temperature and time on the properties of the films were investigated by UV-Vis absorption, fluorescence and circular dichroism spectra. The results show that annealing treatment had no significant effect on the properties of Myr-PMPE-1, including UV-Vis absorption, fluorescence and optical activity. The maximum absolute value of dissymmetry factor (|g _max|) was 1.62 × 10⁻⁴. On the other hand, annealing treatment significantly affected the properties of Myr-PMPE-2. Without annealing or being annealed below 100°C, Myr-PMPE-2 films show almost no Cotton effect. In contrast, when annealed above 120°C, the absorption and emission of Myr-PMPE-2 films slightly red shifted with increasing annealing temperature and annealing time. Most importantly, the intensity of CD signals increased significantly and the optical activity of Myr-PMPE-2 films markedly increased. After annealing at 140°C for 4 h, the |g _max| of Myr-PMPE-2 films was increased up to 3.07 × 10⁻³, about one order of magnitude higher than that of Myr-PMPE-1 films. __________ Translated from Acta Polymeric Sinica, 2008, 3 (in Chinese)     

Novel synthetic approach for optical resolution of cryptophanol-A: a direct access to chiral cryptophanes and their chiroptical properties

The separation by crystallization of the pair of cryptophane diastereomers 1 a and 1 b, obtained in 1:1 ratio by treating racemic anti cryptophanol-A (2) with (-)-camphanic acid chloride, provided a substantial amount of optically pure material (diastereomeric excess>98 %). Subsequent hydrolysis afforded the optically pure cryptophanol-A enantiomers (+)-2 and (-)-2, which were submitted to nucleophilic substitution reactions to provide cryptophane-A (+)-3 and cryptophane monoester (-)-4 in optically pure form. The chiroptical properties of the new cryptophanes 1-4 were investigated by using circular dichroism spectroscopy, and the absolute configuration of the molecules was clearly established. These new cryptophanes represent additional interesting examples for studying the Cotton effect of interacting multichromophoric systems. Moreover, this novel approach presents numerous advantages over the other methods developed so far to obtain optically pure cryptophanes, and compounds (-)-2, (+)-2, and (-)-4 can give access to new enantiopure functionalized cryptophanes with host-guest properties similar to those of cryptophane-A.     

Solvent-induced switching of the macromolecular helicity of poly[(4-carboxyphenyl)acetylene] induced by a single chiral amino alcohol

Cis–transoidal poly[(4-carboxyphenyl)acetylene] (poly- 1 ) complexed with optically active amines and amino alcohols showed an induced circular dichroism (ICD) in the ultraviolet–visible region because of a predominantly one-handed helix formation in water and in dimethyl sulfoxide (DMSO). The Cotton effect signs of the poly- 1 /chiral amino alcohol complexes were inverted in the presence of water, whereas the ICD pattern of the poly- 1 /chiral amine complexes showed no change, regardless of the water content. These results demonstrated that the helix sense of poly- 1 induced by optically active amino alcohols through noncovalent acid–base interactions could be switched by changes in the solvent ratio in the DMSO–water mixtures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3625–3631, 2003     

Convenient synthesis of fully and partially deuterated stereoregular poly(phenylacetylene)s bearing a carboxy pendant and helicity induction on the polymers with chiral amines and its memory

Poly[(4-carboxyphenyl)acetylene] and its derivatives deuterated in the main chain and/or on the phenyl group (poly- 1 's) were conveniently synthesized by the polymerization of 4-ethynylbenzoic acid or its derivative deuterated on the phenyl group in the presence of bases with a water-soluble rhodium complex in water or deuterium oxide. The obtained polymers possesses highly cis–transoidal stereoregular structures according to NMR and Raman spectroscopy. Possible deuterium isotope effects of these partially and fully deuterated poly- 1 's during the helicity induction with chiral amines and its memory assisted by achiral amines were investigated. The thermal cis–trans isomerization of the methyl esters of poly- 1 's was also studied with ¹H NMR spectroscopy. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4711–4722, 2004     

Inherently chiral molecular clips: synthesis, chiroptical properties, and application to chiral discrimination

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-TrpOMeHCl) 3.5 times stronger than the L-enantiomer (KD/KL=3.5).     

Four distinctive 1-D lanthanide carboxylate coordination polymers: Synthesis,crystal structures and spectral properties

Four novel lanthanide coordination polymers [Pr(mal)(OH)(bipy) · 2H₂O]_n (1), {[Dy¹(SBA)₃(H₂O)₂][Dy²(SBA)₃(H₂O)₂] · 4H₂O}_n (2), {[Tb(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (3) and {[Sm(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (4) (Hmal = maleic acid, HSBA = 4-sulfobenzoic acid, OHnicH = 6-hydroxynicotinic acid and bipy = 2,2′-bipyridine) have been synthesized and determined by single crystal X-ray diffraction. Complex 1 is a 1-D helical chain with seven-coordinated praseodymium centers. Complex 2 forms 1-D chain-like molecular structure containing two crystallographically unique dysprosium centers, the Dy¹ center is seven-coordinated while Dy² is eight-coordinated. The isomorphous complexes 3 and 4 exhibit an unprecedented 1-D chain-like polymeric structure through hydroxyl oxygen atoms of bridging Onic²⁻ anions linking up the neighboring central ions, and there exist three types of 6-OHnicH ligands in the structural unit which is rare for lanthanide carboxylate complexes. The photophysical properties of these complexes were studied using ultraviolet absorption spectra, fluorescence excitation and emission spectra.     

Cobalt(II) and silver(I) coordination polymers containing flexible bis (benzimidazol-1-yl)hexane ligands: synthesis,crystal structures,sensing and photocatalytic properties

Two new ternary metal coordination polymers (CPs), namely, {[Co₂(BTC)(L)]·0.25H₂O}_n ( 1 ) and [Ag(HIPA)(L)]_n ( 2 ) (H₄BTC = 1,2,3,4-butanetetracarboxylic acid, H₂IPA = isophthalic acid, L = 1,6-bis(5,6-dimethylbenzimidazol-1-yl)hexane) were hydrothermally synthesized and characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray diffraction, and powder X-ray diffraction (PXRD). 1 exhibits unusual 2D network with point symbol {4³.6³}₂{4⁶.6⁶.7³}. 2 possesses 1D chain structure which is further extended into a 3D supramolecular network via O–H···O hydrogen-bonding and π–π stacking interactions. 1 and 2 can selectively detect benzaldehyde (BZH), Fe³⁺ (just 1 ) and Cr₂O₇²⁻ (just 2 ) ions in water via the luminescence quenching process. Furthermore, the photocatalytic activities of two CPs were evaluated for degradation of methylene blue (MB) and methyl violet (MV) under UV irradiation.     

Synthesis and property of helical poly(phenylacetylene)s bearing chiral ruthenium complexes and real space imaging of meso- and nanoscopic structures by atomic force microscopy

Novel sets of helical poly(phenylacetylene)s bearing a chiral ruthenium (Ru) complex with opposite chirality (Δ and Λ forms) as a bulky pendant (poly- 1 and poly- 2 ) were synthesized through the polymerization of the corresponding optically pure phenylacetylenes with a rhodium catalyst, and their structures in solution and morphology on solid substrates were investigated with NMR, ultraviolet–visible, and circular dichroism (CD) spectroscopies and with atomic force microscopy (AFM), respectively. The obtained cis–transoidal polymers (poly- 1 and poly- 2 ) showed characteristic Cotton effects in the region of metal-to-ligand charge transfer of the chiral Ru pendants. Poly- 1 and poly- 2 were thought to have a predominantly one-handed helical conformation induced by the chiral pendants. However, the apparent Cotton effects derived from the helically twisted π-conjugated polymer backbone could not be observed, probably because of the strong chiral chromophoric pendants. However, in the AFM images, the helical polymers adsorbed on mica could be easily discerned as isolated strands, and the visualization and discrimination of the right- and left-handed helical structures of the chiral polymers were achieved by high-resolution AFM imaging. On the basis of the AFM observations together with the CD measurements and computational calculation results, possible structures of poly- 1 and poly- 2 were examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4621–4640, 2004     

Functionalized poly(phenylene‐alt‐bithiophenes): Synthesis,chiroptical properties,and interaction with chiral amines

New functionalized, (a)chiral poly(phenylene‐alt‐bithiophene)s were prepared and their chiroptical properties were studied. The polymers were prepared by a Stille coupling reaction and were functionalized with protected carboxylic acid and amino functions (tert‐butyl ester and BOC respectively). The polymers are present as well conjugated rigid rods in solution, which (chirally) aggregate in nonsolvents and film. In a next step, the protecting group (tert‐butyl ester in case of the carboxylic acid) was removed. Aggregation of this polymer can be induced by addition of amines; if chiral amines are used, the polymer chains chirally stack. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4817–4829, 2008     

Syntheses,structures, and optical properties of two cadmium complexes with chelidamic acid

[Cd₂(C₇H₃NO₅)₂ · 4(H₂O)] _n · 3nH₂O · 0.5n(CH₃OH) (1) and [Cd₃(C₇H₂NO₅)₂ · 10(H₂O)] · 2H₂O ·0.5CH₃OH (2) were synthesized and characterized by X-ray single-crystal diffraction. The crystal structure of 1 reveals that both Cds are seven-coordinate with pentagonal bipyramid geometries. Coordination polyhedra are interlinked into a 1-D chain, further linked by hydrogen bonds into a 3-D network. Complex 2 is a discrete structure, then independent [Cd₃(C₇H₂NO₅)₂ · 10(H₂O)] are linked by hydrogen bonds into a 3-D network. The optical properties of 1 and 2 were investigated with fluorescent spectra; both exhibit strong green luminescence probably originating from π–π* transition of the ligand.     

Synthesis of organic–inorganic chiral block poly(methylphenylsilane) functional polymers,and study of their optical and chiroptical properties

Polysilanes upon UV irradiation give rise to silyl macroradicals which are capable to initiate radical polymerization. Hence, chiral block functional polysilanes were synthesized by UV irradiation of poly(methylphenylsilane) (PMPS) with a vinyl chiral monomer, (R)‐N‐(1‐phenylethyl)methacrylamide (R‐NPEMAM). The synthesized copolymer samples were characterized by FTIR, NMR, and UV–vis spectroscopy. The number and weight average molecular weights of PMPS and synthesized chiral‐block‐PMPS were measured by GPC analysis. Two glass transition temperatures (T_g) of the synthesized materials clearly indicate the formation of chiral‐block‐PMPS copolymers. SEM analysis also indicated the synthesized organic–inorganic block copolymers. The optical and chiroptical properties of the synthesized materials were studied. The cotton effect is observed not only at 276 nm due to aromatic ring of the chiral monomer units but also at 325 nm which is associated with the Si–Si conjugation of PMPS block of synthesized functional polysilanes. Such tunable chirality may find potential application in optoelectronics. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3626–3634     

Two novel interpenetrated zinc(II) and cadmium(II) coordination polymers based on 4-imidazole-benzoate: Syntheses,crystal structures and properties

Two novel interpenetrated coordination polymers, [Zn(IBA)₂] _n (1) and {[Cd(IBA)₂(H₂O)]·4H₂O} _n (2), have been synthesized by using 4-imidazole-benzoic acid (HIBA) as ligand under hydrothermal conditions. Complex 1 crystallizes in a chiral space group and has a two-fold interpenetrated 2D network structure with (4,4) topology, while complex 2 is a 3D porous dia network with four nets interpenetrating each other. The SHG activity of 1 and the photoluminescent property of 2 have been investigated. Supported by the National Natural Science Foundation of China (Grant Nos. 20731004 & 20721002) and the National Basic Research Program of China (Grant No. 2007CB925103)     

A 4-fold interpenetrated metal-organic diamondoid framework: synthesis,crystal structure,and properties

The coordination polymer, [Cu₂(bpp)₄Cl₂]Cl₂, was prepared by self-assembly of benzo[f] [1,10]phenanthroline-6,7-dicarboxylic acid and bpp [bpp = 1,3-bis(4-pyridyl)propane] with CuCl₂·2H₂O, and determined by X-ray crystallographic diffraction, IR spectrum, and thermal analysis. The complex features a 3-D 4-fold interpenetrated metal–organic framework with diamondoid topology. There are two sets of diamondoid frameworks independently constructed by bpp bridging the same copper centers, and the two sets of diamondoid frameworks interpenetrate one another to form an interesting 4-fold interpenetrating 3-D architecture.