Chiral and Noncentrosymmetric Metal–Organic Frameworks Featuring a 2D → 3D Parallel/Parallel Inclined Subpolycatenation

Abstract

Five chiral and noncentrosymmetric metal−organic frameworks, namely, {[Co(TIPA)(trans-chdc)( 5), have been synthesized based on the N-center tripodal TIPA ligand, where TIPA is tris[4-(1Himidazol-1-yl)-phenyl]amine, H 3 btc is 1,3,5-benzenetricarboxylic acid, trans-H 2 chdc is trans-1,4-cyclohexanedicarboxylic acid, and H 2 seb is sebacic acid. Complexes 1 and 2 are isostructural, crystallize in the chiral orthorhombic space group P2 1 2 1 2 1 , and contain a 2D → 3D parallel/parallel inclined subpolycatenation based on (6,3) layers. The two sets of layers of subpolycatenation are interconnected by right-handed Co(trans-chdc) helical chain, forming a self-catenated framework. Complexes 3 and 4 are also isostructural and crystallize in the chiral monoclinic space group C2. They also contain a 2D → 3D parallel/parallel inclined subpolycatenation based on (6,3) layers. Complex 5 crystallizes in the noncentrosymmetric space group Pna2 1 . Similarly to complexes 1−4, it also contains a 2D → 3D parallel/parallel inclined subpolycatenation based on (6,3) dinuclear Zn-TIPA layers. Meanwhile, the btc 3− ligand with a trimonodentate coordination mode connects the dinuclear Zn unit to form a 2D (6,3) Zn-btc layer. The combination of the two types of interconnected 2D nets results in a self-catenated framework. SHG measurements on complexes 1−5 reveal that complexes 1 and 2 display modest SHG responses that are approximately 3 and 4 times that of KH 2 PO 4 (KDP). The SHG responses of 3 and 4 are about the same as those of 1 and 2, respectively. Complex 5 has a strong SHG response, and its SHG efficiency is approximately 10 times that of KDP. In addition, the photoluminescent properties and thermal stabilities of these complexes were studied in the solid state.

Construction of Noninterpenetrating and Interpenetrating (4-Fold and 8-Fold) 3-D Cd(II) Networks with Tris(1,2,4-triazol-4-yl)phenyl)amine Modulated by Aromatic Dicarboxylate Coligands

“…Prior to our report, several N-donor ligands based on triphenylamine, such as tri­(4-(1 H -imidazol-1-yl)­phenyl)­amine ( TIPA ), tri­(4-pyridylphenyl)­amine ( TPPA ), and tris­(4-(1 H -1,2,4-triazol-1-yl)­phenyl)­amine ( TTPA ), have enjoyed great popularity for construction of various coordination polymers (Scheme ). − It is worthwhile to note that TTPA-4 in our report is different from the reported TTPA ligand that features covalent linkage between N4 atom of 1,2,4-triazole (instead of N1 atom in TTPA ) and triphenylamine, thus allowing for unique N1,N2-bridging mode. Furthermore, the strong σ donor properties of 4s-TAZ unit enable TTPA-4 an effective and strongly coordinating linker that ensures the MOFs robustness.…”

Two Novel Self-Catenated Metal–Organic Frameworks with Large Accessible Channels Obtained by a Mixed-Ligand Strategy: Adsorption of Dichromate and Ln3+ Postsynthetic Modification

“…In this work, we synthesized a new tripodal ligand, tris­[4-(1 H -imidazol-1-yl)]­phosphine oxide (tipo), as the building unit (Scheme ). Similar to N-centered analogues, such a ligand of triangular shape, medium flexibility, and long spacing can give highly porous and robust frameworks. − However, the same construction features are also beneficial for entangled motifs, and combinations of porosity and entanglements are very rare cases. − Moreover, the PO group can coordinate a metal ion to expand the network connectivity or to provide a potential adsorption site. Successfully, the mixed-ligand strategy resulted in two MOFs with unusual patterns of self-catenation: namely, [Cd 3 (bdc)­(HCOO) 2 (tipo) 2 (H 2 O) 2 ]·2NO 3 ·6DMF ( 1 ) and [Zn 8 (OH) 4 (bpdc) 6 (tipo) 4 ]·16DMF ( 2 ).…”