Picric acid–naphthalene 1/1 π complex, C6H3N3O7.C10H8. A disordered structure

Synthesis, growth, optical, mechanical, thermal, dielectric, and SHG properties of Triethylaminium picrate (TEAP) single crystal for nonlinear optical applications

Triethylaminium picrate (TEAP) crystals were grown using the slow evaporation solution growth method at ambient (35 °C) temperature. Salt was synthesized from Picric acid, and Triethylamine and methanol was used as solvents. The solution was mixed at a 1:1 ratio and evaporated slowly, produced yellow colour single crystal of TEAP with an average dimension of 19 × 8 × 5 mm3. The structure of the compound was determined by single-crystal X-ray diffraction (SCXRD) study, which confirms that the crystal is belongs to Orthorhombic crystal system, and its crystallinity was confirmed by the Bragg peak in the powder X-ray diffraction pattern. The superamolecular characteristic of the TEAP was confirmed by the Hirshfield analysis. CHN elemental analysis confirmed the stoichiometry and chemical composition of the synthesized complex salts. FT-IR and Polarized Raman spectral analyses confirmed the presence of different functional groups in the complex. UV-vis-NIR study identified the optical transmission window and the lower (TEAP) cut-off wavelength. Vickers' microhardness analysis determined the mechanical stability of the grown crystal. Studies of dielectric and AC conductivity were analyzed as a function of frequency. The thermogravimetry (TG) and differential thermal analysis (DTA) techniques were used to investigate the thermal behaviour of the material. The Kurtz-Perry powder technique was used to analyze the crystal's nonlinear optical properties (NLO) and found that its SHG efficiency was 1.5 times higher than that of potassium dihydrogen phosphate (KDP). The results from the obtained characterizations conclude that the TEAP crystal could be useful for NLO applications.

Cocrystals in the Cambridge Structural Database: a network approach

To obtain a better understanding of which coformers to combine for the successful formation of a cocrystal, techniques from data mining and network science are used to analyze the data contained in the Cambridge Structural Database (CSD). A network of coformers is constructed based on cocrystal entries present in the CSD and its properties are analyzed. From this network, clusters of coformers with a similar tendency to form cocrystals are extracted. The popularity of the coformers in the CSD is unevenly distributed: a small group of coformers is responsible for most of the cocrystals, hence resulting in an inherently biased data set. The coformers in the network are found to behave primarily in a bipartite manner, demonstrating the importance of combining complementary coformers for successful cocrystallization. Based on our analysis, it is demonstrated that the CSD coformer network is a promising source of information for knowledge-based cocrystal prediction.

Charge transfer complexes as colour changing and disappearing–reappearing colour materials

Charge transfer complexes, made of suitably chosen electron-rich and electron-deficient components, can perform as vanishing colour, disappearing–reappearing colour and colour changing materials.

Hirshfeld surface analysis of crystal packing in aza-aromatic picrate salts

The structures of picrate salts of extended aza-aromatic bases have been determined and systematically analyzed using the Hirshfeld surface approach.

X-Ray Crystallographic Analysis of Picrates

Picric acid forms stable picrates with various organic molecules through pi- bonding or ionic bonding, and such picrates have been very useful for identification and qualitative analysis. As it seemed desirable to determine the crystal structures and the bonding mode of picrates of basic organic compounds, we have investigated the crystal structures of aromatic hydrocarbons, aromatic amino compounds, heterocyclic compounds and so on. A series of our studies on the crystal structure of basic organic compounds have shown that the complexes of picric acid and aromatic hydrocarbons are formed through pi-bonding, and those of aromatic heterocyclic compounds are formed through ionic and hydrogen bonding; in addition, some of them also have pi-bonding.