Noncovalent Interactions and Impact of Charge Penetration Effects in Linear Oligoacene Dimers and Single Crystals

Abstract

Non-covalent interactions determine in large part the thermodynamic aspects of molecular packing in organic crystals. Using a combination of symmetry-adapted perturbation theory (SAPT) and classical multipole electrostatics, we describe the interaction potential energy surfaces for dimers of the oligoacene family, from benzene to hexacene, including up to 5000 configurations for each system. An analysis of these surfaces and a thorough assessment of dimers extracted from the reported crystal structures underline that high-order interactions (i.e., three-body non-additive interactions) must be considered in order to rationalize the details of the crystal structures. A comparison of the SAPT electrostatic energy with the multipole interaction energy demonstrates the importance of the contribution of charge penetration, which is shown to account for up to 50% of the total interaction energy in dimers extracted from the experimental single crystals; in the case of the most stable co-facial model dimers, this contribution is even larger than the total interaction energy. Our results highlight the importance of taking account of charge penetration in studies of the larger oligoacenes.

γ‐Herringbone Polymorph of 6,13‐Bis(trimethylsilylethynyl)pentacene: A Potential Material for Enhanced Hole Mobility

“…The variation in the long‐axis displacement is thus in accordance with the report by Brédas et al. on the existence of multiple stable oligoacene dimer configurations …”

“…The variation in the long-axis displacement is thus in accordance with the report by BrØdas et al on the existenceo fm ultiple stable oligoacene dimer configurations. [34] Hirshfeld surface (HS) analysis [35] and 2D fingerprint analysis [36] were employed to gain insights into the packinga rrangementsi np olymorphs 1 and 2.D istinct 2D fingerprint plots ( Figure S3 in the Supporting Information) obtained for 1 and 2 Figure 1. View perpendicular to the crystallographic a axis showing a) 1D columnarpacking in 1 with as lip-stacked arrangemento fthe aromatic rings and b) the g packing motif in 2;the weak intermolecular interactions that link adjacent p-stacks in c) 1 (CÀH···HÀC) and d) 2 (CÀH···p); the interplanar separation in e) 1 andf)2;view alongthe crystallographic a*axis of g) 1 and h) 2. confirm that they have different packings.…”

Steric “attraction”: not by dispersion alone

“…The electrostatic term is thus almost entirely due to charge penetration (see Figure S7 in Supporting Information File 1 ), which increases exponentially at shorter range. The non-electrostatic term grows at a slower pace with shorter d since it depends both on exchange, which increases exponentially, and dispersion, which increases slower, i.e., as 1/ d 6 [ 66 ]. Similar behavior of E Cpen and E exch is rooted in their dependence on the extent of density overlap [ 67 ] and the following expression connecting them has been suggested as far back as 1970 [ 68 ]: E exch = – E Cpen ( a + b × d ), where a and b are empirical parameters.…”

Halogen in materials design: Revealing the nature of hydrogen bonding and other non-covalent interactions in the polymorphic transformations of methylammonium lead tribromide perovskite

“…Halogen compounds in which halogen-assisted non-covalent interactions feature prominently have found diverse applications in crystal engineering [1], medicinal chemistry [2], supramolecular chemistry [3] materials [4][5][6] and drug design [7]. The halogens in molecules have the ability to donate electron density from electron rich lone-pair orbitals and to accept hydrogen atoms from other molecules to form hydrogen bonds, an important non-covalent interaction [8].…”