Synthesis, growth and characterization of a new derivative 4-ethoxy-N-methyl-4-stilbazolium besylate monohydrate single crystal

Abstract

A new organic material 4-ethoxy-N-methyl-4-stilbazolium besylate monohydrate, a derivative in the stilbazolium family, known for efficient nonlinear optical materials, has been synthesized for the first time. Employing the slow evaporation technique, optically transparent good quality single crystals of size 15 mm×10 mm×5 mm were grown from methanol. The cell dimensions obtained by single crystal X-ray diffraction studies reveal that the crystal belongs to the monoclinic system. Functional groups of the grown crystal were identified from FTIR and NMR spectral analysis. UV−vis−NIR studies show that the crystal is transparent in the wavelength range 460–1100 nm. The thermal stability of the compound was determined by thermal analyses of the specimen.

Introduction

Among the various classes of materials investigated worldwide, ionic organic crystals are of special interest due to their advantageous mechanical, chemical and thermal properties. Especially, 4-N, N-dimethylamino 4′-N'-methyl-stilbazolium tosylate (DAST) is a promising material due to its much larger electro-optic coefficient (r₁₁=92±9 pm/V at λ=720 nm), NLO properties (d₁₁=1010±110 pm/V at λ=1318 nm) and lower dielectric constant (ε=5.2) [1], [2], [3]. Accordingly DAST crystals work well for highly efficient and high speed electro-optic applications [4], [5], [6] as well as THz generation and detection [7], [8], [9]. Research has shown that DAST has the possibility to be further optimized to get new derivatives that possess higher order optical nonlinearities and better characteristics for the growth of high-optical-quality single crystals for various applications using different crystal growth techniques [10], [11], [12], [13], [14], [15]. We have reported the synthesis, crystal growth and nonlinear optical properties of a series of stilbazolium derivatives that were obtained by modifying the structure of the DAST salt [16], [17], [18], [19]. In this study we report on the synthesis and investigations of 4-ethoxy-N-methyl-4-stilbazolium besylate monohydrate (EMSB) crystal, which is a new derivative in the stilbazolium family to the best of our knowledge.