Journal of Molecular Structure 1224 (2020) 129065 Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: www.elsevier.com/locate/molstr Growth, spectral, laser damage and hirshfeld surface studies on configurationally locked 2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene) malononitrile (OH1) single crystal- A potential terahertz emitter S. Karthick a,b , A. Santha a , D. Ganesh c , K. Thirupugalmani d , S. Ganesamoorthy e , A.K. Chaudhary c , S. Brahadeeswaran a,∗ a Crystal Research Laboratory, Department of Physics, Bharathidasan Institute of Technology, Anna University, Tiruchirappalli-620024, India b Department of Physics, Muthayammal Engineering College, Rasipuram, Namakkal-637 408, India c Advanced Center of Research in High Energy Materials (ACRHEM), University of Hyderabad, Hyderabad-500046, India d Department of Physics, ERK Arts and Science College, Dharmapuri 636905, India e X-ray Scattering and Crystal Growth Section, Materials Science Group, CMPD, IGCAR, Kalpakkam, India a r t i c l e i n f o Article history: Received 26 June 2020 Revised 9 August 2020 Accepted 10 August 2020 Keywords: OH1 single crystals Laser damage threshold Hirshfeld surface studies Nonlinear optics Terahertz generation a b s t r a c t We report on the growth, spectral, optical, laser damage and Terahertz (THz) wave generation studies and Hirshfeld analysis of the pyrrolidine-based, configurationally locked, polyene single crystals 2-(3-(4- hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene) malononitrile (OH1), a potential organic material for THz generation. The laboratory synthesized OH1 was verified for its composition and crystalline phase using Carbon–Hydrogen–Nitrogen (CHN) analysis and powder X-ray diffraction method respectively. The functional groups of OH1 were confirmed through Fourier transformed infrared analysis whereas its band gap energy was calculated using the UV–Vis spectrum recorded on (100) plate of thickness of about 1 mm. The laser damage studies performed by employing Q-switched Nd:YAG laser revealed that the OH1 crystals could withstand laser fluences of the order of about 2.21 GW/ cm 2 .Further, the OH1 sin- gle crystals were effectively used for the generation of intense THz waves using indigenously developed setup which comprises of a Ti: Sapphire laser (with 140 fs pulses) and detection using a pyroelectric sen- sor. Furthermore, 3D Hirshfeld surfaces and 2D finger print plots of OH1 were supportive in decoding the intermolecular interaction behaviour and the packing structure of the crystals. © 2020 Elsevier B.V. All rights reserved. 1. Introduction In recent years there has been progressive growth in the field of generation and detection of Terahertz (THz) waves as they possess interesting features such as low energy, non- ionizing and non-invasive [1–7] which make them suitable for applications in the areas of homeland security, biologi- cal imaging, non-destructive evaluation, etc. [8–10]. Nonlin- ear optical (NLO) methods such as optical rectification (OR) and difference frequency generation (DFG) are being routinely employed to generate the THz waves using potentially NLO active organic materials such as 4-N,N-dimethylamino-4 ′ -N ′ - ∗ Corresponding author. Department of Physics, University College of Engineer- ing (UCE), Bharathidasan Institute of Technology (BIT) Campus, Anna University, Tiruchirappalli-620024, Tamil Nadu, India. E-mail address: sbrag67@yahoo.com (S. Brahadeeswaran). methylstilbazoliumtosylate (DAST) [11,12], N-benzyl-2-methyl-4- nitroaniline (BNA) [3], 4-dimethylamino-N-methyl-4-stilbazolium- p-chlorobenzenesulfonate (DASC) [13], N,N-dimethylamino-4 ′ - N ′ -methylstilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) [14], 2-(3-(4-hydroxystyryl)−5,5-dimethylcyclohex-2-enylidene) malononitrile (OH1) [15], (2-(5-methyl-3-(4-(pyrrolidin-1- yl)styryl)cyclohex-2-enylidene) malononitrile) (MH2) [16] as they possess relatively low dielectric constant and large non- linear optical susceptibilities as compared to those of inorganic materials [17–19]. However, device fabrication with such organic THz crystals is still hindered by problems such as difficulties in growing reproducibly large size crystals, stability in normal am- bient, incorporation of foreign particles and/or solvent inclusions in the crystals and less robust against strong optical pumping etc. and are required to be optimized [20,21]. amongst the crystals mentioned above, the OH1, a configurationally locked, organic phenolic polyene and non-ionic organic compound, whose crystal https://doi.org/10.1016/j.molstruc.2020.129065 0022-2860/© 2020 Elsevier B.V. All rights reserved.