Ancillary Ligands Dependent Structural Diversity of A Series of Metal–Organic Frameworks Based on 3,5-Bis(3-carboxyphenyl)pyridine

A series of novel multidimensional
transition metal–organic
frameworks (MOFs), [Cu­(Hbcpb)2]n (1), [Co­(bcpb)]n (2), [Co­(Hbcpb)2(1,4-bib)]n (3), {[M­(bcpb)­(1,4-bimb)]·xH2O}n (M = Co (4), Cu (5),
Ni (6), x = 1 for 5, 2
for 4 and 6), [Co­(bcpb)­(4,4′-bibp)]n (7), {[Co­(bcpb)­(4,4′-bibp)]·2H2O}n (8), and [Ni2(bcpb)2(4,4′-bimbp)2]n (9), were synthesized under hydrothermal
conditions in the presence of N-donor ancillary ligands [H2bcpb = 3,5-bis­(3-carboxyphenyl)­pyridine, 1,4-bib = 1,4-bis­(1H-imidazol-4-yl)­benzene,
1,4-bimb = 1,4-bis­(imidazol-1-ylmethyl)­benzene, 4,4′-bibp =
4,4′-bis­(imidazol-1-yl)­biphenyl, 4,4′-bimbp = 4,4′-bis­(imidazol-1-ylmethyl)­biphenyl].
Their structures have been determined by single-crystal X-ray diffraction
analyses and further characterized by elemental analyses, IR spectra,
powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses.
By adjusting the reaction pH, the H2bcpb ligand is partially
deprotonated to give the Hbcpb– form in 1 and 3, and completely deprotonated to afford the bcpb2– form in 2 and 4–9. Complex 1 exhibits a two-dimensional (2D)
(3,6)-connected kgd topology with the Schläfli symbol of (43)2(46·66·83). The three-dimensional (3D) framework of 2 is
defined as a (4,4)-connected pts topology with the Schläfli
symbol of (42·84). Complex 3 displays a (4,6)-connected pcu topology with the Schläfli
symbol of (412·63) built from 44 2D nets with the help of 1,4-bib. Complexes 4–6 are isomorphism and show a 3D (3,5)-connected mbm framework
with the Point Schläfli symbol of (4·62)­(4·66·83). The supramolecular isomers of 7 and 8, resulted from the different pH in the
reaction, exhibit (3,5)-connected (42·67·8)­(42·6) 3,5-L2 and (4,6)-connected (44·610·8)­(44·62) fsc topology, respectively. Complex 9 can be regard
as an unprecedented (3,5)-connected 3D 3,5-T1 frameworks with the
point Schläfli symbol of (42·65·83)­(42·6). The results revealed that the crystal
architectures and the coordination modes of H2bcpb are
attributed to the factors, including metal cations, pH, and the N-donor
ancillary ligands.

一系列新颖的多维过渡金属-有机框架（MOFs），包括[Cu-(Hbcpb)2]n（1）、[Co-(bcpb)]n（2）、[Co-(Hbcpb)2(1,4-bib)]n（3）、{[M-(bcpb)-(1,4-bimb)]·xH2O}n（M = Co（4）、Cu（5）、Ni（6）、x = 1 对 5，2 对 4 和 6）、[Co-(bcpb)-(4,4′-bibp)]n（7）、{[Co-(bcpb)-(4,4′-bibp)]·2H2O}n（8）和[Ni2(bcpb)2(4,4′-bimbp)2]n（9），在存在N-供体辅助配体[H2bcpb = 3,5-双(3-羧基苯基)吡啶, 1,4-bib = 1,4-双(1H-咪唑-4-基)苯, 1,4-bimb = 1,4-双(咪唑-1-基甲基)苯, 4,4′-bibp = 4,4′-双(咪唑-1-基)联苯, 4,4′-bimbp = 4,4′-双(咪唑-1-基甲基)联苯]的条件下，于水热条件下合成。通过调节反应pH值，H2bcpb配体部分去质子化，在1和3中形成Hbcpb-形式，而在2和4-9中完全去质子化，形成bcpb2-形式。复合物1表现出二维（2D）（3,6）连接的kgd拓扑结构，Schläfli符号为(43)2(46·66·83)。复合物2的立体框架被定义为三维（3D）（4,4）连接的pts拓扑结构，Schläfli符号为(42·84)。复合物3显示由44个二维网络借助1,4-bib构建的（4,6）连接的pcu拓扑结构，Schläfli符号为(412·63)。复合物4-6为同构体，并展示三维（3,5）连接的mbm框架，Point Schläfli符号为(4·62)­(4·66·83)。7和8的超分子异构体，由反应中的不同pH值产生，分别表现出（3,5）连接的（42·67·8）­(42·6) 3,5-L2和（4,6）连接的（44·610·8）­(44·62) fsc拓扑结构。复合物9可被视为前所未有的（3,5）连接的3D 3,5-T1框架，Point Schläfli符号为(42·65·83)­(42·6)。结果表明，晶体结构和H2bcpb的配位模式归因于金属阳离子、pH值以及N-供体辅助配体等因素。