Chiral Coordination Polymers with SHG-Active and Luminescence:An Unusual Homochiral 3D MOF Constructed from Achiral Components.

Six new coordination polymers, namely,[Cd(SO4)(4-abpt)(H2O)]n·3nH2O (1), [Cu3(CN)3(4-abpt)2]n(2), [Cd(D-cam)(2-PyBIm)(H2O)]n(3), [Co(D-Hcam)(cptpy)]n(4), [Cd(D-cam)(btmb)]n(5), and [Cd2(D-cam)(L-cam)(btmbb)]n(6) (4-abpt = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole,D-H2cam = d-camphoric acid, 2-PyBIm = 2-(2-pyridyl)benzimidazole,Hcptpy = 4′-(4-carboxyphenyl)-3,2′:6′,3″-terpyridine,btmb = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, btmbb = 4,4′-bis(1,2,4-triazol-1-ylmethyl)-1,1′-biphenyl),have been synthesized under hydro(solvo)thermal conditions. Theirstructures were determined by single-crystal X-ray diffraction analysisand further characterized by elemental analysis, infrared spectra,powder X-ray diffraction, circular dichroism, and thermogravimetricanalysis. Complex 1features a 3D porous metal–organicframework, which is a rare example to obtain a homochiral compoundfrom achiral components. Complex 2exhibits a 2D polymericnetwork constructed from μ2-cyanide, μ2-4-abpt, and monodentate 4-abpt ligands. Complex 3is a homochiral 1D helical chain polymer. Complex 4displays a 1D ladder-like polymeric structure in which cptpy–is tetradentate and D-Hcam–actsas a side arm. Complex 5displays a homochiral 2D networkwith (4,4) topology. Complex 6shows a [Cd2(D-cam)(L-cam)]n(4,4)-connectednetwork with a paddle-wheel Cd2(COO)4asnode, which is further pillared by a btmbb spacer into a 3D metal–organicframework. d-Camphoric acid underwent racemization underhydrothermal conditions. Cd(II) complexes 1, 3, and 5crystallize in chiral space groups, and theircircular dichroism spectra exhibit obvious positive or negative Cottoneffects. Moreover, 1, 3, and 5are SHG-active, and the SHG efficiency, respectively, is 0.15, 0.4,and 0.4 times as much as that of KH2PO4. All the complexes exhibit relatively high thermal stability. 1, 3, 5, and 6emitviolet luminescence originating from ligand-centered emission. [ABSTRACT FROM AUTHOR]