Strong optical limiting effects of two Ag(I)-bridged metal-organic polymers

Two Ag(I)-bridged metal-organic polymers: 2D double-crossed layer polymer {[Ag(bpfp)] · NO3 · H2O)}n (bpfp = N,N′-bis(3-pyridylformyl)-piperazine) (1) and 1D zigzag chain polymer {[Ag(btx)] · NO3}n (btx = 1,4-bis(triazol-1-ylmethyl)-benzene) (2) have been prepared and structurally characterized by single crystal diffraction. Their third-order nonlinear optical (NLO) properties and optical limiting (OL) effects were determined by Z-scan technique. The results show that both polymers possess strong optical nonlinear absorption and optical nonlinear refraction, and exhibit strong OL effect to nanosecond and picosecond incident pulsed laser. By comparing the optical nonlinearities of the polymers and purely bpfp and btx ligands, we find that the incorporation of Ag ion can largely enhance the optical nonlinearities of organic molecules attached. DFT calculation further confirms the corporate contributions of Ag ions and bridge ligands to the optical nonlinearities.