Studies on two interesting microporous polymeric clusters {[Et4N](2)[MS4Cu4(CN)(4)]}(n) (M = Mo or W) with three-dimensional open frameworks: synthesis, structural characterization, strong optical non-linearities and large optical limiting properties

Reactions combining stoichiometric amounts of (Et4N)(2)MS4 (M=Mo or W) and CuCN (1:4) in pyridine afforded interesting three-dimensional cluster polym ers with open frameworks {[Et4N](2)[MS4Cu4(CN)(4)]}(n) (M=Mo 1 or W 2). Cry stal structure determination shows that the anionic MS4Cu4 units bridged by cyanide produce three-dimensional channels running down the crystallograph ic a axis. An alternative way to view this framework is in terms of the dia mond structure, where C has alternately been replaced by a MS4Cu4 aggregate and C-C by two parallel cyanide bridging ligands. In these intersecting ch annels the shortest distances between Cu atoms along the b and c axes are 1 5.22 and 8.11 Angstrom respectively. Non-linear optical properties of the t wo clusters were investigated first with an 8 ns pulsed laser at 532 nm. Th ese two clusters exhibit large optical limiting performance with limiting t hreshold values of 0.28 for 1, 0.15 J cm(-2) for 2 respectively. Both compo unds show strong third-order NLO absorption effects (alpha(2) 1.5x10(-9) 1, 1.6x10(-9) m W-1 2) and self-focusing performance (n(2) 1.84x10(-16) 1, 1. 22x10(-16) m(2) W-1 2) in 3.64x10(-5) 1 and 2.93x10(-5) mol dm(-3) 2 DMF so lution separately. The corresponding effective NLO susceptibilities chi((3) ) are 4.58x10(-9) 1 and 5.12x10(-9) esu 2 while the corresponding hyperpola rizabilities (gamma((1))=1.15x10(-29) and gamma((2))=1.26x10(-29) esu) are also reported.