Experimental and database-transferred electron-density analysis and evaluation of electrostatic forces in coumarin-102 dye

Abstract

The electron-density distribution of a new crystal form of coumarin-102, a laser dye, has been investigated using the Hansen-Coppens multipolar atom model. The charge density was refined versus high-resolution X-ray diffraction data collected at 100 K and was also constructed by transferring the charge density from the Experimental Library of Multipolar Atom Model (ELMAM2). The topology of the refined charge density has been analysed within the Bader `Atoms In Molecules' theory framework. Deformation electron-density peak heights and topological features indicate that the chromen-2-one ring system has a delocalized π-electron cloud in resonance with the N (amino) atom. The molecular electrostatic potential was estimated from both experimental and transferred multipolar models; it reveals an asymmetric character of the charge distribution across the molecule. This polarization effect is due to a substantial charge delocalization within the molecule. The molecular dipole moments derived from the experimental and transferred multipolar models are also compared with the liquid and gas-phase dipole moments. The substantial molecular dipole moment enhancements observed in the crystal environment originate from the crystal field and from intermolecular charge transfer induced and controlled by C-H···O and C-H···N intermolecular hydrogen bonds. The atomic forces were integrated over the atomic basins and compared for the two electron-density models.

The enrichment ratio of atomic contacts in crystals, an indicator derived from the Hirshfeld surface analysis

“…These molecules have large aromatics parts research papers IUCrJ (2014). 1, 119-128 Christian Jelsch et al Enrichment ratio of atomic contacts 121 Table 1 Example of Hirshfeld contact surfaces and derived 'random contact' and 'enrichment ratios' for the coumarin-102 crystal (Bibila Mayaya Bisseyou et al, 2012).…”

Cu[Ni(2,3-pyrazinedithiolate)2] Metal–Organic Framework for Electrocatalytic Hydrogen Evolution

“…The relative stability of the closed-shell d 10 Cu­(I) system compared to that of the d 9 Cu­(II) system is likely to make the cleavage of the Cu–N bond favorable. Further CM5 (Bader) charge analysis − also revealed that upon H atom addition, the charge on the Cu centers decreases from 0.70(0.98) e – to 0.53(0.70) e – , consistent with the reduction of Cu­(II) to Cu­(I). On the other hand, the CM5 and Bader charges on the Ni centers remain unchanged (Table S8) for all of the structures, suggesting no change in the formal oxidation states of the Ni centers.…”

Molecular Insights into Water–Chloride and Water–Water Interactions in the Supramolecular Architecture of Aconine Hydrochloride Dihydrate

“…Therefore, we employed the electron transfer-based MoPro-ELMAM2 model to gain insights into the electron density, strength, and nature of short contacts . Furthermore, several studies , have confirmed that both multipole refinement and MoPro-ELMAM2 models exhibit a consistent trend in the topological values at the BCPs and demonstrate excellent quantitative and qualitative agreement. In this study, our primary focus lies in investigating hydrogen bonding interactions involving the H···O and H···Cl – contacts.…”