Homochiral Coordination Polymers Research Articles

Exploring enantioselective recognition of dTMP-Co-bpe coordination polymer for natural amino acids using molecular simulations and circular dichroism.

The 1D homochiral coordination polymer (CP-1) {[Co(dTMP)(bpe)2(H2O)3]·9H2O}n was constructed by using 2'-deoxy thymidine 5'-monophosphate disodium salt (dTMP·2Na), and auxiliary ligand bpe (1,2-bis(4-pyridyl)ethene) and characterized by single-crystal XRD, PXRD, IR, UV-visible, CD and TGA analyses. Molecular simulations revealed the selective chiral behaviour of CP-1 towards phenylalanine and histidine, as indicated by their higher binding free energies compared to other amino acids. Theoretical parameters were also compared with experimental UV-visible verdicts. Notably, the D-enantiomers of phenylalanine and histidine demonstrated strong bonding abilities and optimal configurations for probing and distinguishing them from their L-counterparts. These findings led to propositions suggesting that the dissimilarities between these D and L amino acid forms and their binding orientations with CP-1 may contribute to alterations in the CD signal. CP-1 exhibited a robust inherent circular dichroism (CD) signal in aqueous solutions, modulated by the presence of specific amino acids, namely D/L phenylalanine and D/L histidine. Leveraging the measurement of CD signal intensity, a sensor capable of detecting unmodified amino acids has been developed. Unlike previously reported approaches that relied on complex chemical reactions between initially CD-silent molecules and probed amino acids, this new method offers a more straightforward means of amplifying the CD signal. Consequently, this change facilitates a more accurate differentiation between the enantiomers of these specific amino acids compared to others.

Multifunctional Chiral d10-Metal Coordination Polymers: Tunable Photoluminescence and Efficient Second-Harmonic Generation with Circular Dichroic Response.

A series of homochiral coordination polymers (HCPs), [M2(SIAP)2(bpy)2] [M(S)] and [M2(RIAP)2(bpy)2] [M(R)] (M = Zn or Cd, SIAP or RIAP = (S,S)- or (R,R)- 2,2'-(isophthaloylbis(azanediyl))di-propionic acid, bpy = 4,4'-bipyridine), is successfully synthesized through solvothermal reactions, self-assembling d10 metal cations, chiral dicarboxylic ligands, and π-conjugated bipyridyl ligands. The HCPs crystallize in the extremely rare triclinic chiral space group, P1, and present 3D framework structures attributed to the strong intermolecular interactions, such as hydrogen bonds and π-π stacking. Due to the unique crystal structures, the title compounds reveal efficient photoluminescence emission across a broad visible range, with significant brightness and color tuning by varying the excitation wavelength. Moreover, they exhibit efficient phase-matched second-harmonic generation (SHG) with very high laser-induced damage thresholds, essential for high-power nonlinear optical (NLO) applications. Intriguingly, the title compounds exhibit a measurable contrast in the SHG response under right- and left-handed circularly polarized excitation, thereby providing a unique case of SHG circular dichroism from the chiral centers of SIAP2- or RIAP2- ligand packed in the noncentrosymmetric environment. These exceptional attributes position these HCPs as promising candidates for multifunctional materials, with potential applications ranging from NLO devices to tailored luminescent systems with polarization control.

Synthesis, crystal structures and optical properties of homochiral coordination polymers with noncentrosymmetric structures

Synthesis, crystal structures and optical properties of homochiral coordination polymers with noncentrosymmetric structures

Ligand‐Tuned Perylene Diimide‐Based Versatile Coordination Polymers for Photoluminescent Sensing and Optoelectronics

AbstractChiral self‐sorting is essential for the establishment of structures in nature and chemistry. Owing to similarities among recognition sites of enantiomers and shared conformational labilities, high‐fidelity chiral self‐sorting constitutes a substantial challenge. Coordination polymers (CPs) with a high surface area and chemical tunability have potential applications in luminescent probes and optoelectronics. However, it is difficult to synthesize micro‐/nano‐scale CPs with high conductivity for optoelectronics. Here, a series of perylene diimide (PDI)‐based CPs with large π‐planes is synthesized by tuning ligands for use in various sensors. A cadmium (Cd)‐based coordination polymer with leucine (LeuPDI‐Cd) exhibits a unique chiral self‐recognition phenomenon when two enantiomeric ligands are mixed with the metal source because homochiral CPs are thermodynamically more stable than their heterochiral analogs. In addition, photoluminescent (PL) LeuPDI‐Cd CPs can detect ethylenediamine with high sensitivity and selectivity. Micro‐/nano‐sized CPs with methionine (MetPDI‐Cd) are used in photodetectors and chemiresistive sensors for the detection of toxic phenylhydrazine. Theoretical calculations reveal that the enhanced conductivity is related to the reduced energy gap, which occurs after adsorption of phenylhydrazine onto the CP surface. These results demonstrate the feasibility and versatility of PDI‐based CPs for applications in PL sensing and optoelectronics through the tuning of PDI ligands.

Coordination-driven chiral self-assembly: Synthesis, structures and vapor adsorption properties of Zn(II) and Ag(I) complexes derived from two helical pyridylamide ligands

Four complexes were synthesized and characterized from two helical pyridylamide ligands. A view of the geometry of these complexes discloses the self-discriminating and self-recognition process in the coordination-driven chiral assembly. • Four new complexes derived from two helical pyridylamide ligands have been synthesized and characterized. • The crystal structures of the four complexes reveal the chiral self-assembly process in the coordination reaction. • Cyclic voltammetric measurements and methanol vapor adsorptions for the complexes are investigated. Two helical pyridylamide ligands N 2 ,N 6 -bis(2-(nicotinamido)phenyl)pyridine-2,6-dicarboxamide ( L 1 ) and N 2 ,N 6 -bis(2-(isonicotinamido)phenyl)pyridine-2,6-dicarboxamide ( L 2 ) have been designed and synthesized. Four complexes, namely, {[Zn( L 1 )I 2 ]‧2CH 3 OH‧H 2 O} n ( 1 ), [Ag 2 ( L 1 ) 2 ]‧(NO 3 ) 2 ( 2 ), {[Ag( L 2 )NO 3 ]‧H 2 O} n ( 3 ), and {[Ag( L 2 ) 2 ]‧2H 2 O} n ( 4 ) were obtained via the solvent evaporation method from the reaction of the ligands with Zn(II) or Ag(I) ions respectively. The two ligands together with four complexes were structurally determined by single-crystal X-ray diffraction and additionally characterized by infrared spectroscopy, element analysis and powder X-ray diffraction. The crystal structures reveal different chiral self-assembly processes in the reaction of the helical liands with Zn(II) or Ag(I) ions. Complexes 1 , 2 and 4 exhibit as a heterochiral coordination polymer or binuclear metallamacrocycle, while complex 3 exists as a homochiral coordination polymer. Besides, the structural differences between complexes 3 and 4 show that the reaction ratio of the ligand with metal ions has obvious influences on the coordination configuration. Furthermore, thermogravimetric analysis and methanol vapor adsorption properties of the synthesized complexes have been investigated, and cyclic voltammetric measurements of complexes 2 – 4 were carried out as well.

Homochiral coordination polymers of Zn(II) and Pb(II) with interesting three-dimensional helicates

Based on a designed enantiomerically pure chiral ligand H3L, two interesting homochiral metal−organic frameworks (HMOFs), namely {[Zn3(L)2(H2O)2]∙2H2O}n (1) and {[Pb(HL)(H2O)]∙H2O}n (2), have been solvothermally synthesized (H3L = (S)-4'-(((1-carboxyethyl)amino)methyl)-[1,1′-biphenyl]-3,5-dicarboxylic acid). Complexes 1 and 2 are novel three-dimensional metal−organic helicates with different structural motifs. In 1, anionic (L)3− ligands bridge trimetallic Zn-clusters to form a [3,6]-connected architecture of (63)2(612·83) topology. In particular, each trimetallic Zn-cluster is the node of six strand 21 helical chains consisting of four right-handed helical chains and two left-handed helical chains. In 2, zwitterionic (HL)2− ligands link PbII ions into a 3-connected 103-topological helicate composed of 21 helical chains extending along three crystal axes, and two thirds of which are left-handed. Interesting enough, the chiral ligand H3L not only transferred its inherent chirality to the synthesized complexes 1 and 2, but also induced unexpected helical chirality. Furthermore, the morphologies, thermal stabilities and solid-state optical properties including CD spectra, and nonlinear optical and luminescent properties of compounds 1 and 2 were also carried out. Compounds 1 and 2 exhibit interesting fluorescence emissions and obvious second-order nonlinear activity in addition to the excellent thermal stability of their dehydrated frameworks, indicating that the HMOF materials have great potential in optical devices.

Homochiral coordination polymers based on proline-derivative: structures, magnetic properties, and selective detection of Cr2O72− anion

By incorporating semi-rigid terephthaloyl mono proline-derived ligand [H2TMPro ​= ​terephthaloyl-mono(l-proline)] with the ancillary dipyridyl ligands [bpea ​= ​1,2-bis(4-pyridyl)ethane and bipy ​= ​4,4′-bipyridine], five new homochiral coordination polymers were synthesized. Compounds [Cu3(TMPro)2(μ3-OH)2]·4H2O (1) and [Zn3(TMPro)2(μ3-OH)2]·4H2O (2) are isostructural complicated 3D frameworks, which contain the intertwined right- and left-handed helical chains built from the butterfly-shaped [Cu4(μ3-OH)2(RCOO)6] units. Compound [Cu2(TMPro)2(bpea)2(H2O)2]·7H2O (3) displays a 3D framework composed of Cu1-TMPro left-handed helical chains and Cu2-TMPro right-handed helical chains connected by the bpea ligands. Compound [Cd4(TMPro)4(bpea)6]·10H2O·4C2H5OH (4) features a 3-fold interpenetrating 3D framework with 5-connected hexagonal bnn topological net constructed from the {Cd-TMPro} chains and bpea ligands. Compound [Ni(TMPro)(bipy)(H2O)3] (5) exhibits a {Ni-bipy}2+ 1D chain decorated by the TMPro2− anions. Magnetic susceptibility measurements indicate ferromagnetic exchange interactions between Cu(II) ions in 1. Photoluminescence spectra of 2 show corresponding emission bands of TMPro2− anions. Additionally, for 2, the Ksv value of 553 ​M−1 and detection limit of 70 ​μM imply it can detect the Cr2O72− anion.

Enantioselective chiral sorption of 1-phenylethanol by homochiral 1D coordination polymers

Enantiomeric selectivity is shown within the pores of a 1D coordination polymer, dependent on the nature of the pore space.

Three-dimensional homochiral coordination polymers of Eu(III) and Tb(III): Synthesis, structure determination, and optical properties

Self-assembly of the corresponding europium and terbium salts with designed chiral ligand (S)-5-((2-carboxy-5-oxopyrrolidin-1-yl)methyl)isophthalic acid (H3L) generated two novel 3D coordination polymers {[Eu(L)]·0.5CH3CN}n (1) and {[Tb(L)]·0.5CH3CN}n (2). Single-crystal X-ray diffraction analyses reveal that 1 and 2 are isostructural metal-organic frameworks built from four-stranded helixes. Complexes 1 and 2 are intriguing homochiral porous architectures with 6,6-connected (48∙66∙8)(413∙62) topology, whose homochirality was further confirmed by their solid-state circular dichroism spectra. Thermal analyses disclose that the desolvated frameworks of 1 and 2 can maintain their structural stability below 370 ​°C. Solid-state photoluminescence studies show that 1 and 2 exhibit strong characteristic Eu(III) and Tb(III) emissions with long lifetimes of 1.31 and 1.35 ​ms, respectively. In addition, 1 and 2 also exhibit significant second harmonic generation activities with their intensities of about 0.29 and 0.31 times larger than that of potassium dihydrogenphosphate, respectively. Very importantly, the excellent thermostabilities and strong red and green emissions of 1 and 2 are of great significance for further exploration of their applications in optical devices.

Chiral Cd(II) Coordination Polymers Based on Amino Acid Derivatives: The Effect of Side Chain on Structure

Homochiral coordination polymers have emerged as promising candidates for a range of chirotechnological applications, including asymmetric catalysis and enantioselective separation. The use of liga...

Luminescent 3D homochiral coordination polymers of europium(III) and terbium(III) based on amino acid-functionalized isophthalic acid

The use of purely chiral fluorescent tricarboxylic ligand (S)-5-(((1-carboxy-2-phenylethyl)amino)methyl)isophthalic acid (H3L) led to isostructural lanthanide-based homochiral metal-organic frameworks, [EuCl(HL)]n (1) and [TbCl(HL)]n (2), in which every zwitterionic ligand HL connects five metal ions and metal nodes Eu3+ and Tb3+ adopt eight- and seven-coordinated modes, respectively. They are 5-connected novel 3D homochiral coordination polymers consisting of interesting triple-stranded helixes and display the strong characteristic emissions corresponding to Eu3+ and Tb3+. Both 1 and 2 exhibit high thermal stability, which was demonstrated by TGA. In addition, the chiroptical activity of 1 and 2 was also investigated by CD spectra.

Heterochiral or Homochiral Self‐Assembly: Mercury(II), Cadmium(II), and Spontaneous Resolution of Silver(I) Complexes Derived from a Racemic Bis(pyridyl) Ligand

A novel racemic bis(pyridyl) ligand (rac‐L) was designed and synthesized by Schiff condensation reaction. Five complexes, [Hg2(LR)(LS)Cl4]·2CH3CH2OH (1), [Cd(LR)(LS)Cl2]n (2), {[Cd(LR)(LS)SO4(H2O)]·11H2O}n (3), {[Ag(LR)2]NO3·CH3CN}n (4a) and {[Ag(LS)2]NO3·CH3CN}n (4b) have been synthesized and characterized. The different geometric features of complexes 1–4 were determined by single‐crystal X‐ray diffraction. The crystal structures show that the self‐assembly with racemic ligands can lead to homochiral or heterochiral complexes, through self‐recognition or self‐discrimination of the ligand units. Complex 1 exists as a 26‐membered binuclear heterochiral macrocycle. Complexes 2 and 3 form 1D mesomeric looped chain coordination polymers with different heterochiral self‐assembly types. More interestingly, two novel 2D homochiral coordination polymers 4a and 4b were obtained as racemic conglomerates via spontaneous resolution. Furthermore, the thermal stabilities and luminescence properties of complexes 1–4 were investigated.

Temperature-induced solid-to-solid transformation in helical homochiral coordination polymers.

The reactions of (R)- and (S)-4-(1-carboxyethoxy)benzoic acid (H2CBA) with 1,3-bis(2-methyl-1H-imidazol-1-yl)benzene (1,3-BMIB) ligands afforded a pair of homochiral coordination polymers (CPs), namely, poly[[[μ-1,3-bis(2-methyl-1H-imidazol-1-yl)benzene][μ-(S)-4-(1-carboxylatoethoxy)benzoato]zinc(II)] monohydrate], {[Zn(C10H8O5)(C14H14N4)]·H2O}n or {[Zn{(S)-CBA}(1,3-BMIB)]·H2O}n (1-L), and poly[[[μ-1,3-bis(2-methyl-1H-imidazol-1-yl)benzene][μ-(R)-4-(1-carboxylatoethoxy)benzoato]zinc(II)] monohydrate] (1-D). Three kinds of helical chains exist in compounds 1-D and 1-L, which are constructed from ZnII atoms, 1,3-BMIB ligands and/or CBA2- ligands. When the as-synthesized crystals of 1-L and 1-D were further heated in the mother liquor or air, poly[[μ-1,3-bis(2-methyl-1H-imidazol-1-yl)benzene][μ-(S)-4-(1-carboxylatoethoxy)benzoato]zinc(II)], [Zn(C10H8O5)(C14H14N4)]n or [Zn{(S)-CBA}(1,3-BMIB)]n (2-L), and poly[[μ-1,3-bis(2-methyl-1H-imidazol-1-yl)benzene][μ-(R)-4-(1-carboxylatoethoxy)benzoato]zinc(II)] (2-D) were obtained, respectively. The single-crystal structure analysis revealed that 2-L and 2-D only contained one type of helical chain formed by ZnII atoms and 1,3-BMIB and CBA2- ligands, which indicated that the helical chains were reconstructed though solid-to-solid transformation. This result not only means the realization of helical transformation, but also gives a feasible strategy to build homochiral CPs.

Homochiral Cu(I) Coordination Polymers Based on a Double-Stranded Helical Building Block from Achiral Ligands: Symmetry-Breaking Crystallization, Photophysical and Photocatalytic Properties.

A pair of homochiral coordination polymers, [Cu(DPT)]n (1M and 1P, HDPT = 3,5-di-4-pyridinyl-2H-tetrazole), were assembled from achiral precursors. Crystal structure analysis showed that they are chiral three-dimensional (3D) coordination polymers based on a new double-stranded helical building block that is composed of two different 1D helices. Interestingly, rare symmetry-breaking crystallization was observed, in which the possibility of obtaining enantio-enriched bulk product with excessive M enantiomers (1-A) was obviously higher than that for P enantiomers (1-B) as demonstrated in multiple, repeated experiments with single-crystal diffraction and vibrational circular dichroism (VCD) spectra. Moreover, compound [Cu(DPT)]n shows good chemical stability in water, with pH values ranging from 3 to 13, as well as in many common organic solvents. Photophysical properties, including thermochromic properties and two-photon excited luminescence, were studied, and the potential for applications in temperature sensing was exhibited. In addition, the photocatalytic degradation of methylene blue in water indicated that compound [Cu(DPT)]n can be used as a photocatalyst.

QCM based enantioselective discrimination of enantiomers by a pair of serine derived homochiral coordination polymers

Decoding enantioselective molecular interactions between sensors and guests into readable signal represents a great challenge in developing selective sensing technology. In this work, a pair of serine derivatives based homochiral coordination polymer (HCP) enantiomers, (L)-SA-Cd and (D)-SA-Cd, were synthesized and explored as enantioselective sensors towards guest enantiomers. Quartz crystal microbalance (QCM) technology was employed to indicate the gravimetric change of (L)- and (D)-SA-Cd towards variable chiral guests, and an enantioselective factor of 1.72 ± 0.15, 1.81 ± 0.08, 1.37 ± 0.03 and 2.89 ± 0.09 were achieved for lactic acid, menthol, valinol and 1-phenylethylamine (PEA), respectively. PEA was further selected to comprehensively study the enantioselectivity via electrochemical tests, HPLC analysis and theoretical calculations. By comparison with state-of-art works, the enantioselective discrimination for PEA enantiomers is better than a vast majority of similar reports. (L)- and (D)-form of SA-Cd exhibited mirror behaviors towards guest enantiomers, and control experiments indicated the role of HCP construction in enhancing enantioselectivity. H-bonding effect was found to be the binding force between SA-Cd and PEA, as verified by FT-IR and UV–Vis titration studies. Further DFT calculations revealed the existence of conformation oriented H-bonding between the chiral –OH groups of serine fragment and –NH2 group of PEA. The findings indicate that HCP construction represents an effective strategy for promoting enantioselectivity, and monitoring gravimetric change could be a promising general method in decoding most of the enantioselective recognition process.

Synthesis and structural characterization of homochiral coordination polymers with imidazole-based monocarboxylate ligands.

Chiral Na[(S)-LR] (R = Me, 1a; iPr, 1b; CH2iPr, 1c, and (S)-secBu, 1d) and Na[(R)-LR] (R = Me, 1a') compounds were synthesised following standard procedures. New compounds 1d and 1a' were analytically and spectroscopically characterised. 1a and 1c were structurally identified by single-crystal X-ray diffraction methods as homochiral 2D coordination polymers, {Na(H2O)[(S)-LMe]}n and {Na[(S)-LCH2iPr]}n, respectively. Both (S)-2alkyl,2-(1H-imidazol-1-yl)acetate anions displayed unprecedented coordination modes in these coordination polymers: μ3κ2OκO' for 1a and μ4κ2Oκ2O' for 1c. Enantiomeric species 1a', {Na(H2O)[(R)-LMe]}n, showed the same X-ray powder diffractogram (XRPD) as 1a, in agreement with a similar crystal structure. DFT calculations on the [LR]- anions confirmed their coordination capabilities as ditopic linkers. In fact, the reaction of Na[LR] with several metal salts yielded the following coordination polymers: {Ag[(S)-LMe]}n, 2a, {Ag[(R)-LMe]}n, 2a', {Cu[(S)-LR]2}n (R = Me, 3a; iPr, 3b), {Cu[(R)-LMe]}n, 3a', {Zn[(S)-LR]2}n (R = Me, 4a; iPr, 4b; (S)-secBu, 4d) and {Zn[(R)-LMe]2}n, 4a'. For the known compounds 3a and 4a, this procedure is a new synthetic route that avoided high temperature reaction conditions. New complexes 2, 3a', b, and 4a', b, d were characterised by elemental analysis, infrared and XRPD methods and complex 2a by single-crystal X-ray diffraction. This complex is also a two-dimensional coordination polymer in which the [(S)-LMe]- anion acts as a μ4κN,κ2O,κ2O' bridging ligand. Compounds 1-4a' are the first examples of homochiral coordination polymers with imidazole-monocarboxylate ligands based on non-natural amino acids. Preliminary studies on the metal-catalysed preparation of chiral α-aminophosphonates were carried out but, unfortunately, no enantioselectivity was observed.

Molecular tectonics: from a rigid achiral organic tecton to 3D chiral Co and Fe coordination networks.

An achiral organic tecton bearing four coordinating sites of the pyridyl type leads to the formation of iso-structural 3D helical coordination polymers when combined with Co(SCN)2 and Fe(SCN)2 achiral neutral complexes. Their formation occurs during the self-assembly process in the solid state, which leads to crystals composed of homochiral coordination polymers.

Гомохиральный координационный полимер на основе меди(II), S-яблочной и бифенил-3,3',5,5'-тетракарбоновой кислот

Нагреванием раствора нитрата меди(II), S-яблочной (H3mal) и бифенил-3,3',5,5'-тетра­карбоновой (H4bptc) кислот в смеси вода—N,N-диэтилформамид получен координационный полимер [Cu8(S-mal)4(bptc)(H2O)12]·0.5H4bptc⋅7.5H2O. Кристаллическая структура установлена методом РСА. Соединение обладает трехмерным гомохиральным каркасом, имеющим каналы, заполненные кристаллизационными молекулами тетракарбоновой кислоты и воды. Состав и строение полученного координационного полимера подтверждены данными рентгеновской дифракции на порошках, ИК спектроскопии, термогравиметрического и элементного анализа.

Homochiral Coordination Polymers Based on Amino Acid-Functionalized Isophthalic Acid: Synthesis, Structure Determination, and Optical Properties

Three interesting homochiral metal–organic frameworks (HMOFs), namely, [Zn8(L)4(OH)4(H2O)2]n (1), {[Cd2(HL)2(H2O)4]·6H2O}n (2), and {[Pb2(HL)2]·CH3OH·2.5H2O}n (3), have been hydro/solvothermally synthesized through the reaction of the designed chiral ligand (S)-5-(((1-carboxyethyl)amino)methyl)isophthalic acid (H3L) with corresponding metal sources. Crystallographic analysis indicates that the triply deprotonated H3L ligands can adopt anionic (L)3– and zwitterionic (HL)2– forms, various coordination modes, and versatile hydrogen-bonding connections to construct interesting HMOFs with unique architectures. Complexes 1 and 2 are two-dimensional (2D) coordination polymers, but their structural motifs are very different. In 1, anionic (L)3– ligands bridge tetrametallic Zn-clusters to form a 2D layer with (3,6)-connected kgd net. In 2, zwitterionic (HL)2– ligands link CdII ions to generate two types of independent wave-like layers of 63 topology, and the two independent layers are further connected to form the...

Three-dimensional copper(II) carboxylates based on 4,4′,4″-benzene-1,3,5-triyltris(benzoic acid)

The homochiral coordination polymers [Cu4(CH3OH)(H2O)4(Hbtb)(S-mal)2]•4H2O and [Cu4(CH3OH)(H2O)4(Hbtb)(R-mal)2]•4H2O were synthesized by heating S- or R-malic acid (H3mal), 4,4′,4″-benzene-1,3,5-triyltris(benzoic acid) (H3btb), and copper(II) acetate in an aqueous methanolic solution. The reaction with copper(II) nitrate in aqueous dioxane afforded the coordination framework [Cu6(C4H8O2)3(H2O)3(btb)4]•4C4H8O2•10H2O, which does not contain chiral ligands. The compositions and crystal structures of the new compounds were determined by single-crystal X-ray diffraction and confirmed by X-ray powder diffraction, IR spectroscopy, thermogravimetric and elemental analysis.