Third-order nonlinear optical properties of three Mn(II)-4,4 '-bpy coordination polymers and crystal structure of three-dimensional network [Mn(SO4)(4,4 '-bpy)(H2O)(2)](n)

We determined the third-order nonlinear optical (NLO) properties of coordin ation polymers [Mn(SO4)(4,4 ' -bpy)(H2O)(2)](n) (1), and [Mn(N-3)(2)(4,4 ' -bpy)](n) (2) and [{Mn(NCS)(2)(4,4 ' -bpy)(H2O)(2)}(4,4 ' -bpy)](n) (3) by Z-scan technique. Polymers 1 and 2 show strong self-defocusing effects. The ir third-order NLO susceptibility chi ((3)) are 5.0 x 10(-12) esu in a 4 x 10(-4) g cm(-3) DMF solution for I and 1.2 x 10(-11) esu in:a 1.6 x 10(-3) g cm(-3) DMF solution for 2, respectively. These data are comparable to tho se of cluster polymers. Polymer 3 exhibits weaker self-defocusing behavior than polymer 1 and 2. The crystal structure of polymer 1 shows that the com pound exhibits three-dimensional (3-D) layered structure. Every layer is fo rmed in the ac plane by connecting Mn centers via bridging bpy ligands to g enerate parallel -Mn-bpy-Mn- chains, whereas between adjacent layers the -M n-bpy-Mn- chains have an angle of 45 degrees. -Mn-bpy-Mn- chains in differe nt layers are joined by zigzag -Mn-SO42- -Mn-SO4-2 chains leading to the 3- D framework. (C) 2001 Elsevier Science B.V. All rights reserved.