High-pressure synthesis and optical limiting property of cyclic diphenylacetylene oligomer

摘要

New conjugated oligomers were synthesized by reacting diphenylacetylene under high pressure of 0.13-0.76 GPa at 250 and 300 degrees C for 1-10 h. The number-average molecular weight (M) over bar(n), and the weight-average molecular weight (M) over bar(w) increased with pressure, but those values were independent of temperature and time ((M) over bar(n), 320-490; (M) over bar(w), 350-580). Elementary analysis, held desorption mass spectrometry, Fourier transform infrared, and C-13 nuclear magnetic resonance experiments revealed that the oligomer above and including pentamer was a new compound having cyclic structure. Toluene solutions of the oligomer (400 (M) over bar(n)) contained within a quartz cell were irradiated with the pulse from a frequency-doubled Nd : Yag laser at 532 nm. The transmittance of the solution decreased with input fluence, and we observed an optical Limiting property with saturated output fluence. As the concentration of the oligomer increased, the saturated output fluence decreased. The optical limiting property was analyzed according to the reverse saturable absorption mechanism. (C) 1998 John Wiley & Sons, Inc. [References: 29]