Metal–Organic Frameworks Containing Flexible Bis(benzimidazole) Ligands

Eleven coordination polymers constructed from three structurally related flexible bis(benzimidazole) ligands, 1,1′‐(1,4‐butanediyl)bis(2‐methylbenzimidazole) (L 1 ), 1,1′‐(1,4‐butanediyl)bis(2‐ethylbenzimidazole) (L 2 ), and 1,1′‐(1,4‐butanediyl)bis(2‐benzylbenzimidazole) (L 3 ), have been synthesized: [Zn(cin) 2 (L 1 )] · H 2 O ( 1 ), [Zn(cin) 2 (L 2 )] ( 2 ), [Cd(cin) 2 (L 1 )] · H 2 O ( 3 ), [Cd(cin) 2 (L 2 )] ( 4 ), [Ag(MES)(L 1 ) 0.5 ] ( 5 ), [Ag(MES)(L 2 ) 0.5 ] · H 2 O ( 6 ), [Zn(adi)(L 1 )] · H 2 O ( 7 ), [Zn(adi)(L 2 ) 0.5 ] ( 8 ), [Cd(adi)(L 1 )] · 2H 2 O ( 9 ), [Cd(adi)(L 2 )] ( 10 ), and [Cd(adi)(L 3 )] · 2H 2 O ( 11 ), where cin = cinnamate anion, MES = 2‐( N ‐morpholino)ethanesulfonate anion, and adi = adipate dianion. For compounds 1 – 4 , the cin anions are coordinated to metal ions in monodentate mode or bidentate chelating mode, and metal cations are bridged by L 1 or L 2 ligands to form 1‐D chain structures. Compound 5 shows a 1‐D chain structure which comprises a dimeric unit that is built from two silver ions and two MES anions. In compound 6 , silver ions are bridged by MES anions and L 2 ligands to form a 2‐D (6, 3) network while compounds 7 – 9 possess 2D (4, 4) networks. In the structure of compound 8 , there exists a dimeric unit which is built from two zinc ions bridged by four carboxylate groups. Compound 10 exhibits a fourfold interpenetrating diamondoid net, and compound 11 displays a noninterpenetrating diamondoid framework. The luminescent properties for 1 – 11 are also discussed in detail.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)