NMR studies of the reaction between amino-phenylene vinylene thiophene and tetracyanoethylene

Abstract

Amino tricyanovinyl thiophene chromophores (A-TCVT) are prepared by a substitution reaction of amino-phenylene vinylene thiophene (A-PVT) with tetracyanoethylene (TCNE). This reaction does not occur directly. The vinylene double bond in the PVT unit first reacts rapidly with TCNE to form a [2+2] cycloaddition product. It is then reverted to PVT unit prior to the subsequent substitution at 50°C. This reversible cycloaddition converts the cis-isomer of PVT units into the trans-counterparts, thus the final TCNE substituted products can be expected for a better performance as non-linear optical materials. Crown

Synthesis and Characterizations of Highly Fluorinated Poly(arylene ether)s for Quadratic Nonlinear Optics

“…63 Two side reactions have been found to accompany with this reaction: one is the 2 þ 2 cyclic addition of the TCNE to the CdC in the ThV, and the other is the hydrolysis of TCNE when trace of water present in the solvent. 63 The former is a completely reversible reaction, and the cycloaddition product reverted completely to double bond at 50 °C. But this reaction reduced TCNE concentration in the reaction solution.…”

“…The ThV copolymers were then converted to the TCVT polymers by reacting with tetracyanoethylene (TCNE) in DMF. A 100% conversion can be easily obtained for all the ThV polymers when the reaction was conducted at 50 °C in the presence of excess of TCNE . Two side reactions have been found to accompany with this reaction: one is the 2 + 2 cyclic addition of the TCNE to the CC in the ThV, and the other is the hydrolysis of TCNE when trace of water present in the solvent .…”

“…A 100% conversion can be easily obtained for all the ThV polymers when the reaction was conducted at 50 °C in the presence of excess of TCNE. 63 Two side reactions have been found to accompany with this reaction: one is the 2 þ 2 cyclic addition of the TCNE to the CdC in the ThV, and the other is the hydrolysis of TCNE when trace of water present in the solvent. 63 The former is a completely reversible reaction, and the cycloaddition product reverted completely to double bond at 50 °C.…”