Studying the Role of CO···CO, CO···N–O, and N–O···N–O Dipole–Dipole Interactions in the Crystal Packing of 4‑Nitrobenzoic Acid and 3,3′-Dinitrobenzophenone Polymorphs: An Experimental Charge Density Study

An experimental charge density study of 4-nitrobenzoic acid and 3,3′-dinitrobenzophenone polymorphs has been performed to study the role played by various intermolecular interactions in the crystal packing. The study highlights the importance of dipole–dipole interactions analyzed with the help of Bader’s quantum theory of atoms in molecules (QTAIM), low-reduced density gradient (RDG) based topological descriptors of electron density and computations. The molecular pairs held by antiparallel CO···CO, CO···N–O, and N–O···N–O type dipole–dipole interactions were found to contribute significantly toward stability especially in the case of 3,3′-dinitrobenzophenone, Form <b>II</b>. The low-RDG based descriptors were used for understanding the nature of these dipole–dipole interactions, which indicates the involvement of multiple atoms in stabilizing many of these interactions. The significant contributions from the O···C, O···O, and O···N contacts arising from these dipole–dipole interactions in crystal packing are also revealed from the Hirshfeld surface analysis of these crystals

Rational Coformer Selection and the Development of New Crystalline Multicomponent Forms of Resveratrol with Enhanced Water Solubility

We report the development of 10 new cocrystal forms of the nutraceutical compound resveratrol obtained through a rational coformer screening by utilizing the interaction site pairing energy differences computed based on molecular electrostatic potential calculations. A new monohydrate form of resveratrol and 10 novel cocrystals with 9 different coformers were characterized in the study. Among the newly developed solid forms of resveratrol, two of its cocrystals with (1) a Generally Recognized As Safe compound piperazine and (2) the bioactive compound methenamine were subjected to aqueous solubility determination. The newly developed piperazine cocrystal exhibits the highest aqueous solubility among the previously known cocrystals of resveratrol

Synthesis of Octabromoperylene Dianhydride and Diimides: Evidence of Halogen Bonding and Semiconducting Properties

A facile synthesis of octabromoperylene-3,4,9,10-tetracarboxylic dianhydride (Br₈-PDA) (<b>1</b>), its diimides (Br₈-PDIs) (<b>2a</b>–<b>e</b>), and bis-, tris-, and tetra-amino substituted diimides (<b>5a</b>–<b>c</b>) with six, five, and four remaining substitutable Br atoms, respectively, is reported. Octabromination results in facile chemical/electrochemical reduction, radical anion formation, and red-shifted optical properties. For the first time, diverse halogen-bonding interactions were identified in the PDA/PDI, which along with the attractive electronic features enhance the electron-transport characteristics compared to the di-/tetra-brominated PDIs (<b>3</b>/<b>4</b>)