pH-Triggered construction of NLO active CMOFs: change in supramolecular assembly, water clusters, helical architectures and their properties

Abstract

Two different chiral metal–organic frameworks (CMOF), namely, {[Cu₂(1,10-phen)₂(tartrate)H₂O]·8H₂O}_n (1) and {[Cu(1,10-phen)(H₂tartrate)H₂O]·6H₂O}_n (2) [1,10-phen = 1,10-phenanthroline] have been synthesized with an alteration in the pH of the reaction media. Reflux at 85 °C, complex 1 (pH = 4.95) crystallizes in P2₁, while simple stirring at room temperature, complex 2 (pH = 4.10) crystallizes in P2₁2₁2₁ space group. When the solid-state structure of 1 is compared with complex 2, interesting changes in the supramolecular self-assembly are noticed. CMOF 1 features a 1D supramolecular coordination polymer, in stark contrast, CMOF 2 features 1D coordination polymer. We reveal one helicalassembly in 1 whereas three helicalassembly in 2. The CMOFs exhibit solid-state blue luminescence at room temperature and non-linear optical (NLO) activity.