Double helix chain frameworks constructed from bis-benzotriazole building blocks: Syntheses, crystal structures and third-order nonlinear optical properties

Abstract

Reactions of 1,1′-(1,3-propylene)bis-1H-benzotriazole (pbbt) and KSCN with Ni(II) or Co(II) salt lead to the formation of two new double helix chain coordination polymers {[Ni(pbbt) 2(NCS) 2]·H 2O} n 1 and {[Co(pbbt) 2(NCS) 2]·H 2O} n 2. Their third-order nonlinear optical (NLO) properties were determined with a 7 ns pulsed laser at 532 nm. The results show that polymer 2 exhibits large NLO absorptive effects ( α 2 = 1.4 × 10 −9 m W −1), and both of them show strong NLO refractive behaviors with the refractive index n 2 of 3.02 × 10 −18 m 2 W −1 for 1 and 8.23 × 10 −18 m 2 W −1 for 2. The hyperpolarizability | γ| values of 1 and 2 were calculated to be 1.68 × 10 −29 esu and 4.58 × 10 −29 esu, respectively. This indicates that the third-order NLO properties of coordination polymers can be altered through metal ions manipulation.