Obtaining the lattice energy of the anthracene crystal by modern yet affordable first-principles methods

The non-covalent interactions in organic molecules are known to drive their self-assembly to form molecular crystals. We compare, in the case of anthracene and against experimental (electronic-only) sublimation energy, how modern quantum-chemical methods are able to calculate this cohesive energy taking into account all the interactions between occurring dimers in both first-and second-shells. These include both O(N 6)- and O(N 5)-scaling methods, Local Pair Natural Orbital-parameterized Coupled-Cluster Single and Double, and Spin-Component-Scaled-Møller-Plesset perturbation theory at second-order, respectively, as well as the most modern family of conceived density functionals: double-hybrid expressions in several variants (B2-PLYP, mPW2-PLYP, PWPB95) with customized dispersion corrections (–D3 and –NL). All-in-all, it is shown that these methods behave very accurately producing errors in the 1–2 kJ/mol range with respect to the experimental value taken into account the experimental uncertainty. These methods are thus confirmed as excellent tools for studying all kinds of interactions in chemical systems.Financial support by the “Ministerio de Economía y Competitividad” of Spain and the “European Regional Development Fund” through projects CTQ2011-27253, CTQ2012-31914, and Consolider-Ingenio CSD2007-00010 in Molecular Nanoscience, and by the Generalitat Valenciana (ISIC 2012/008 and PROMETEO/2012/053) is acknowledged. The work in Mons is supported by the Belgian National Fund for Scientific Research (FNRS). Y.O. is a FNRS Post-doctoral Research Fellow. J.C.S.G. is a FNRS Visiting Professor

Poling effect on distribution of quenched random fields in a uniaxial relaxor ferroelectric

The frequency dependence of the dielectric permitivity's maximum has been studied for poled and unpoled doped relaxor strontium barium niobate $Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}:Cr^{3+}$ (SBN-61:Cr). In both cases the maximum found is broad and the frequency dispersion is strong. The present view of random fields compensation in the unpoled sample is not suitable for explaining this experimental result. We propose a new mechanism where the dispersion of quenched random electric fields, affecting the nanodomains, is minimized after poling. We test our proposal by numerical simulations on a random field Ising model. Results obtained are in agreement with the polarization's measurements presented by Granzow et al. [Phys. Rev. Lett {\bf 92}, 065701 (2004)].Comment: 7 pages, 4 figure

A very general rate expression for charge hopping in semiconducting polymers

We propose an expression of the hopping rate between localized states in semiconducting disordered polymers that contains the most used rates in the literature as special cases. We stress that these rates cannot be obtained directly from electron transfer rate theories as it is not possible to define diabatic localized states if the localization is caused by disorder, as in most polymers, rather than nuclear polarization effects. After defining the separate classes of accepting and inducing nuclear modes in the system, we obtain a general expression of the hopping rate. We show that, under the appropriate limits, this expression reduces to (i) single-phonon rate expression or (ii) the Miller-Abrahams rate or (iii) a multi-phonon expression. The description of these limits from a more general expression is useful to interpolate between them, to validate the assumptions of each limiting case, and to define the simplest rate expression that still captures the main features of the charge transport. When the rate expression is fed with a range of realistic parameters the deviation from the Miller-Abrahams rate is large or extremely large, especially for hopping toward lower energy states, due to the energy gap law

A Columnar Liquid Crystal with Permanent Polar Order

The self-assembly of axial dipolar subphthalocyanine molecules in the presence of electric fields leads to uniaxially oriented columnar liquid crystalline materials that exhibit permanent polarizationFunding from MINECO (MAT2012-38538-CO3-01, 02 and CTQ2012- 31914), MICINN and MEC (F.P.U. fellowship (JG), CTQ-2011- 24187/BQU, CTQ2011-23659 and Consolider-Ingenio Nanociencia Molecular, CDS2007-00010), Comunidad de Madrid (MADRISOLAR-2, S2009/PPQ/1533), European Research Council (StG-279548), Aragon government, E04, Basque Country Government GI/IT-449-10, Generalitat Valenciana (PROMETEO/ 2012/053), and FEDER is acknowledge

The quantum paraelectric behavior of SrTiO_{3} revisited: relevance of the structural phase transition temperature

It has been known for a long time that the low temperature behavior shown by the dielectric constant of quantum paraelectric $SrTiO_{3}$ can not be fitted properly by Barrett's formula using a single zero point energy or saturation temperature ($T_{1}$). As it was originally shown [K. A. M\"{u}ller and H. Burkard, Phys. Rev. B {\bf 19}, 3593 (1979)] a crossover between two different saturation temperatures ($T_{1l}$=77.8K and $T_{1h}$=80K) at $T\sim10K$ is needed to explain the low and high temperature behavior of the dielectric constant. However, the physical reason for the crossover between these two particular values of the saturation temperature at $T\sim10K$ is unknown. In this work we show that the crossover between these two values of the saturation temperature at $T\sim10K$ can be taken as a direct consequence of (i) the quantum distribution of frequencies $g(\Omega)\propto\Omega^{2}$ associated with the complete set of low-lying modes and (ii) the existence of a definite maximum phonon frequency given by the structural transition critical temperature $T_{tr}$.Comment: 8 pages, 3 figure

Self-assembly of Clicked Star-Shaped Triazines into Functional Nanostructures

Two non-amphiphilic star-shaped 2, 4, 6-tris(1, 2, 3-triazol-4-yl)-1, 3, 5-triazines showing different behavior in terms of self-assembly and luminescent properties are described. They aggregate in the liquid phase to form low-dimensional nanostructures with a variety of morphologies, such as spherical particles, one-hole hollow spheres, toroids, twisted fibers or helical nanotubes, just by varying the conditions of a straightforward reprecipitation method. Aggregation has an opposite effect concerning the fluorescent properties of the proposed compounds, either causing the enhancement or the quenching of the emission after the self-assembly. Quantum chemical calculations have been also performed to assist in the structural and electronic characterization of the two star-shaped compounds

Dual-mode chiral self-assembly of cone-shaped subphthalocyanine aromatics

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/jacs.0c07291Columnar polymers and liquid crystals obtained from π-conjugated cone-shaped molecules are receiving increasing interest due to the possibility of obtaining unconventional polar organizations that show anisotropic charge transport and unique chiroptical properties. However, and in contrast to the more common planar discotics, the self-assembly of conic or pyramidic molecules in solution remains largely unexplored. Here, we show how a molecular geometry change, from flat to conic, can generate supramolecular landscapes where different self-assembled species, each of them being under thermodynamic equilibrium with the monomer, exist exclusively within distinct regimes. In particular, depending on the solvent nature-aromatic or aliphatic-cone-shaped C3-symmetric subphthalocyanine 1 can undergo self-assembly either as a tail-to-tail dimer, showing monomer-dimer sigmoidal transitions, or as a head-to-tail noncentrosymmetric columnar polymer, exhibiting a nucleation-elongation polymerization mechanism. Moreover, the experimental and theoretical comparison between racemic and enantiopure samples revealed that the two enantiomers (1M and 1P) tend to narcissistically self-sort in the dimer regime, each enantiomer showing a strong preference to associate with itself, but socially self-sort in the polymer regime, favoring an alternate stacking order along the columnsFunding from the Spanish MINECO/MCIU [PGC2018-099568-B-I00, CTQ2017-85393-P, CTQ2017-84727-P, ERA-NET/European Commission/MINECO (UNIQUE, SOLAR-ERA.NET Cofund 2 N° 008/ PCI2019-111889-2), and RED2018-102331-T], the Generalitat Valenciana (SEJI/2018/035), and European Feder funds (PGC2018-099568-B-I00) is gratefully acknowledged. IMDEA Nanocien-cia acknowledges support from the “Severo Ochoa” Pro-gramme for Centres of Excellence in R&D (MINECO, Grant SEV2016-0686

Controlling the Host-Guest Interaction Mode through a Redox Stimulus

A proof-of-concept related to the redox-control of the binding/releasing process in a host-guest system is achieved by designing a neutral and robust Pt-based redox-active metallacage involving two extended-tetrathiafulvalene (exTTF) ligands. When neutral, the cage is able to bind a planar polyaromatic guest (coronene). Remarkably, the chemical or electrochemical oxidation of the host-guest complex leads to the reversible expulsion of the guest outside the cavity, which is assigned to a drastic change of the host-guest interaction mode, illustrating the key role of counteranions along the exchange process. The reversible process is supported by various experimental data (1 H NMR spectroscopy, ESI-FTICR, and spectroelectrochemistry) as well as by in-depth theoretical calculations performed at the density functional theory (DFT) level