| The functionalization of complexes is a hot spot in modern coordination chemistry and supramolecular chemistry.The design and synthetic of chiral metal-organic supramolecular compounds are the basis of the study and application of chiral characterization and chiral functional materials,and are also one of the leading research areas in modern functional complex chemistry.Although the study upon chiral metal-organic supramolecular chemistry based on aminoacid-functionalized chiral functional ligands has made a certain progress,the aminoacid-functionalized chiral modification of aromatic polycarboxylic acids ligands are rare,and especially the investigation upon chiral metal-organic supramolecular compounds based on aminoacid-functionalized aromatic polycarboxylic acid ligands are more rare.In this paper,we tried to functionalize5-methyl isophthalic acid with amino acid,and successfully designed and synthesized?S?-5-???1-carboxyethyl?amino?methyl?isophthalic acid?H3L?.The resulting novel chiral aromatic polycarboxylic acid was used as ligand to assemble with metal ions such as Zn???,Pb???,Cd???and Cu???for the construction of metal-organic supermolecules.Through hydro?solvo?thermal reactions as well as controlling reaction conditions,six chiral metal-organic supramolecular complexes,namely,[Zn8?L?4?OH?4?H2O?2]n?1?,{[Pb2?HL?2]·CH3OH·2H2O}n?2?,{[Pb2?HL?2]·10H2O}n?3?,{[Cd2?HL?2?H2O?4]?6H2O}n?4?,{[Cu?HL??H2O?2]?H2O}n?5?and{[Cu6?L?4?bipy?4?H2O?6]?9H2O}n?6?[bipy = 4,4'-bipyridine],were obtained.In this paper,the crystal structures,chiral characteristics,optical properties and thermal stabilities of the six chiral metal-organic supramolecular compounds,especially including non-linear and circular dichroism,were systematically investigated.The asymmetric catalytic performance of the chiral metal-organic framework?MOF?3 in the alkylation reaction of p-tolualdehyde?PTAL?was also been initially studied.These six compounds all crystallize in the chiral space group and belong to pure chiral MOFs determined by single crystal X-ray diffraction analysis and chiroptical properties.In these MOFs,the aminoacid-functionalized5-methyl isophthalic acid ligand H3L exhibits excellent coordination diversity to build up the novel and unique architectures.The coordination polymer 1 is a novel two-dimensional?2D?double-layered structure where [Zn4??3-OH?2] clusters are further double-bridged by carboxyl oxygen atoms into “?Zn?O?”chains.In 1,the ligands L and [Zn4??3-OH?2] can be simplified as 3-connected and 6-connected nodes,respectively,and thereby forming a?3,6?-connected network structure with?43?2?46·66·83?topology.In the plumbum???coordination polymers 2 and 3,both the ligands HL and Pb???ions are 3-connected nodes,but their structures are completely different.2 features a 2D 2-folded interpenetrating structure with a?62·12??6·122?topology,while 3 possesses a 2D network with a 63 topology.Interestingly,3 consists of two independent diastereoisomeric 2D layers which stack up in the ABAB style through interlayered ??? interactions.The strcture of coordination polymer 4 is very similar to that of 3,and it is also a 2D network with a 63 topology.4 also contains two independent chiral layers whose chirality is only determined by the chirality of the ligand HL.Notably,the coordination number of metal ions Cd???in the two independent chiral layers is different,but the two independent chiral layers are also deposited by the ABAB method through interlayered ??? interactions like that in 3.In 1D coordination polymer 5,ligands HL bridge Cu???ions to form left-handed spiral chains,and the chirality of ligands HL is transferred along the chains.Additionally,those helical chains are further linked into a 3D chiral supramolecule through interchain hydrogen-bonding interactions.Compound 6 is a novel 3D coordination polymer containing chiral [Cu6?L?4] nano-cage subunits.In [Cu6?L?4]subunits,the chiral carbons of all ligands L are in the original S-configurations,and the nitrogen atoms of the amino groups in all ligands L adopt the R-configurations due to coordination with metal ions Cu???.As regarded the [Cu6?L?4] subunits as6-connected nodes the architecture in 6 formed by bipy ligands bridging [Cu6?L?4]subunits can be simplified as an ?-Po topology.In conclusion,the aminoacid-functionalized 5-methyl isophthalic acid ligand H3L is a multifunctional chiral spacer.In assemblies with metal ions,the chirality of ligand H3L can be transmitted into the as-synthesized metal-organic supermolecules.Moreover,the orderly combination of chiral ligands and metal ions in thesupramolecular level can also give rise to more chiral elements.As a result,it will endow the as-synthesized metal-organic supermolecules with stronger and richer chiroptical properties,which displays attractive prospect for the development of chiral functional materials.In addition,the as-synthesized metal-organic supermolecule 3 exhibits certain stereochemical catalysis in the asymmetric alkylation of p-Tolualdehyde?PTAL?. |
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