Molecular Crystal Structures and Nonlinear Optical Properties in the Series of Dicyanovinylbenzene and Its Derivatives

Abstract

X-ray single-crystal structures, molecular mechanics (MM) calculations of the optimal molecular dimers, and calculations of the static second-order polarizabilities (β) were performed for a large series of methoxyand dimethylamino-substituted derivatives of dicyanovinylbenzene and some of its analogues having large values of the molecular nonlinear optical susceptibilities. X-ray structural analysis has been performed for 3,4-dimethoxy-and 3,4,5-trimethoxy-dicyanovinylbenzenes (I,Crystal packing analysis and energetic MM calculations revealed the factors responsible for the formation of the centrosymmetric crystals. Compounds III and V were found to form acentric crystal structures (space groups P2 1 and Pc, respectively) and therefore are capable to the second-harmonic generation (SHG) in solid state. Qualitative data have demonstrated that compound V is rather active in SHG in the powder state (using Nd:YAG laser with λ ) 1064 nm) that may be important for its application. On the contrary, the powder of III is not active in SHG despite the "optimal" crystal packing that might be related to the strong absorption of the second harmonic light at λ ) 532 nm, but this compound gives strong SHG signal using the laser light with λ ) 1907 nm. Analysis of the influence of the different substituents in the aromatic ring on the calculated β values in the series of the compounds studied was made.

trans-1-Cyano-2-(2-methoxyphenyl)-1-nitroethylene

“…Bond lengths in molecule (I) do not differ signi®cantly from those found in the other derivatives of 2-aryl-1,1-dicyanoethylene (Antipin, Clark et al, 1998) and are close to the standard bond lengths (Allen et al, 1987) in corresponding %conjugated systems.…”

“…connected by %-conjugated chains of different length. There are derivatives of 2-aryl-1,1-dicyanovinyl and 4-aryl-1,1-dicyano-1,3-butadiene (Antipin et al, 1997;Antipin, Clark et al, 1998;Antipin, Timofeeva et al, 1998;Timofeeva et al, 2000: Nesterov et al, 2000. Molecules of the title compound, (I), have another type of acceptor group.…”

Polymorphism and solvolysis of 2-cyano-3-[4-(N,N-diethylamino)phenyl]prop-2-enethioamide

“…The present investigation is a continuation of a project that includes syntheses and structural studies of polar conjugated organic compounds that crystallize in non-centrosymmetric space groups (Antipin et al, 1998;Nesterov et al, 1998Nesterov et al, , 2000Nesterov, Antipin, Nesterov, Moore et al, 2004;Nesterov, Antipin, Nesterov, Penn et al, 2004). These compounds may ®nd applications in non-linear optical materials (Zyss, 1994;Kuzyk & Dirk, 1998) and in the syntheses of heterocyclic compounds (Brunskill et al, 1984;Nesterov et al, 2002).…”

Three polar derivatives ofN-ethylcarbazole: materials for optical applications

“…Structural data, along with theoretical calculations and experimental measurements, help to reveal the nature of the relevant structure±property relationships. The present investigation is a continuation of our project which incorporates the synthesis, structural studies and evaluation of properties of organic compounds for potential optical applications (Antipin et al, 1997(Antipin et al, , 1998(Antipin et al, , 2001Timofeeva et al, 2000;Nesterov et al, 2000). To our knowledge, no structural information on NLO carbazole derivatives has previously been available.…”