Assembly of [CunIn]-based coordination polymers from cracking the 3D framework of bulk CuIvia flexible N-heterocyclic ligands

Abstract

Solvothermal reactions of CuI with four flexible N-heterocyclic ligands, 1,2-bis(4-pyridyl)ethane (bpe), 1,1′-(1,4-butanediyl)bis-1H-benzimidazole (bbbm), 1,1′-(1,4-butanediyl)bis-1H-benzotriazole (bbbt), and 1,1′-(1,5-pentanediyl)bis-1H-benzimidazole (pbbm), afforded four new [Cu_nI_n]-based coordination polymers, [Cu₃I(μ-I)(μ₃-I)(bpe)₃]_n (1), {[CuI(bbbm)_1.5]·0.25MeCN}_n (2), and [Cu₄(μ₃-I)₄L₂]_n (3: L = bbbt; 4: L = pbbm), respectively. Compounds 1–4 were characterized by elemental analysis, IR and X-ray crystallography. 1 consists of an unique 2D network in which 1D [CuI(bpe)]_n zigzag chains are embroidered alternatively onto the two faces of a 2D [Cu₄(μ-I)₂(μ₃-I)₂(bpe)₂]_n layer through pairs of bpe bridges. 2 contains a 66-membered metallomacrocyclic [CuI(bbbm)_1.5]₆ unit that fuses with its neighbouring ones via sharing Cu atoms to form a 2D (6,3) layer network. 3 or 4 contains a cubanelike [Cu₄(μ₃-I)₄] core, which works as a cross-shaped four-connecting node to link its four equivalent units to form a 2D (4,4) cross-shaped network (3) or acts as a Y-shaped three-connecting node to connect its three equivalent ones to form a 1D double chain (4). In addition, the photoluminescent properties of 1–4 in solid state at ambient temperature were also investigated.