Construction of Open Metal–Organic Frameworks Based on Predesigned Carboxylate Isomers: From Achiral to Chiral Nets

The four‐connected carboxylate ligand N , N , N ′, N ′‐tetrakis(4‐carboxyphenyl)‐1,4‐phenylenediamine (TCPPDA) exists as three stereoisomers: a pair of enantiomers ( δ D 2 ‐ and λ D 2 ‐TCPPDA) and a diastereomer ( C 2 h ‐TCPPDA). TCPPDA was predesigned for the construction of isomeric coordination networks. Reactions of M(NO 3 ) 2 (M=Cu, Zn, Co) or Nd(NO) 3 with TCPPDA under solvothermal conditions gave rise to five novel porous metal–organic frameworks: [Cu 2 ( D 2 ‐tcppda)(H 2 O) 2 ]⋅2 DMSO⋅6 H 2 O ( 1 ), [Cu 2 ( C 2 h ‐tcppda)(H 2 O) 2 ]⋅2 DMSO⋅6 H 2 O ( 2 ), [Co 3 ( D 2 ‐Htcppda) 2 ]⋅4 DEF⋅5 H 2 O ( 3 ), [Nd 2 ( D 2 ‐tcppda)( C 2 h ‐tcppda) 0.5 (DMSO) 3 ]⋅3 DMSO⋅5 H 2 O ( 4 ), and [Zn 4 O( D 2 ‐tcppda) 1.5 ]⋅DMF⋅H 2 O ( 5 ) (DMSO=dimethyl sulfoxide, DEF=diethylformamide, DMF=dimethylformamide). Complexes 1 and 2 are supramolecular isomers, in which all the ligands adopt pseudotetrahedral (both δ D 2 ‐ and λ D 2 ‐TCPPDA) and rectangular ( C 2 h ‐TCPPDA) geometries, respectively. Both compounds connect paddlewheel secondary building units (SBUs) to form three‐dimensional porous networks possessing PtS and NbO nets, respectively. In 3 , all ligands possess pseudotetrahedral (both δ D 2 ‐ and λ D 2 ‐TCPPDA) geometry and link hourglass SBUs to form a three‐dimensional porous framework. Compound 4 contains all three stereoisomers ( C 2 ‐, δ D 2 ‐, and λ D 2 ‐TCPPDA), thus, has both pseudotetrahedral and rectangular geometries. D 2 ‐TCPPDA connects the binuclear neodymium units to generate a two‐dimensional layer, further linked by C 2 h ‐TCPPDA to create a three‐dimensional open framework. In 5 , all the ligands possess pseudotetrahedral geometry ( D 2 ‐TCPPDA), as found in 1 and 3 . However, all the TCPPDA ligands in 5 appear as either the δ D 2 or the λ D 2 form, thus, the whole structure is homochiral. Complex 5 crystallizes in the I 4 1 32 space group and the octahedral SBU in 5 is connected by the enantiopure TCPPDA to generate a three‐dimensional porous network possessing the corundum Al 2 O 3 net. Complexes 1 , 2 , and 5 possess permanent porosity, and 4 and 5 exhibit strong luminescence at λ max =423 and 424 nm, respectively, upon excitation at 268.5 nm.