Nature of Color Diversity in Phenylenevinylene-Based Polymorphs

Abstract

In this work we present a joint experimental and theoretical study of the light emitting properties of (E,E)-2,5-dimethoxy-1,4-bis­[2-(4-carboxylatestyryl)]­benzene, a phenylenevinylene (PV, from now on) derivative in the solid state. Careful crystal growth under different conditions of this PV luminophore yields three different crystals with dissimilar color emissions with maxima ranging between 504 and 565 nm. Single crystal structure elucidations indicate that they correspond to a DMF solvate, denoted 2·DMF (yellow) and two conformational polymorphs named 2α (yellow) and 2β (orange). Analysis of the close contacts and the framework topologies help us to rationalize the different colors observed, not only on the basis of different intramolecular conformations but also of the different intermolecular interactions observed. Particularly, the presence of different C–H···π and π···π interactions in 2α and in 2β polymorphs, respectively, give rise to different supramolecular frameworks with hex and bcu topologies. Theoretical studies reinforce the hypothesis that cooperative π···π interactions in the crystal lattice are responsible for the red-shifted color observed in the polymorph 2β. In fact, in contrast to what is observed with the polymorph 2α, as we incorporate more monomers in the calculations of the optical properties of polymorph 2β, the estimated energy for the vertical excitation from the ground state to the first excited state moves to lower values.

Polymorphism Dependent 9-Phosphoanthracene Derivative Exhibiting Thermally Activated Delayed Fluorescence: A Computational Investigation

“…To control the TADF phenomenon in organic molecules, tailoring of molecular aggregates by introducing a heavier main-group element or a functional group made a point, which mainly affects the crystal packing in the condensed phase. − In such cases, the screening of the polymorphism is an efficient way to explore the luminescent properties, exclusively based on intermolecular interaction in a single crystal. − By analyzing the morphology and packing patterns, Cárdenas et al concluded that there is diversity in the color of different phenylenevinylene-based polymorphs . Nonetheless, the diversity in photophysical properties of acene-based polymorphs cannot be overlooked. − However, the development in organic functional materials that are probed to OLED can be done by controlling the excited states of the chromophores. , Introducing electron-withdrawing substituents is the most efficient way to modify the π-conjugated framework that will tune the luminescence property of the chromophore. − The electronic coupling in such systems can be measured by evaluating the electronic coupling matrix element. , Interestingly, in such systems, the intersystem crossing (ISC) occurs through a charge recombination process, especially where the acceptor chromophore is anthracene and arranged in orthogonal conformation with donor moiety. − As an example, phenothiazine–anthracene compact dyads show such behavior .…”

“…17−19 By analyzing the morphology and packing patterns, Caŕdenas et al concluded that there is diversity in the color of different phenylenevinylene-based polymorphs. 20 Nonetheless, the diversity in photophysical properties of acene-based polymorphs cannot be overlooked. 21−24 However, the development in organic functional materials that are probed to OLED can be done by controlling the excited states of the chromophores.…”

The Effect of Auxiliary Nitrogenated Linkers on the Design of New Cadmium‐Based Coordination Polymers as Sensors for the Detection of Explosive Materials

“…The diversity of supramolecular interactions that can be displayed by a singular material makes it challenging to visualize and understand them and therefore almost unmanageable to relate them with the final properties of the materials. Thinking of a way to solve this problem, the topological description of crystal structures has emerged as a useful tool to explain various material′s physical properties based on the complete structure connectivity [34–37] . Here, the construction of the net can be done by taking into account the initial geometrical data as well as the chemically relevant interactions [38, 39] .…”

“…Thinking of aw ay to solve this problem, the topological description of crystal structuresh as emerged as au seful tool to explain various material'sphysicalproperties based on the complete structure connectivity. [34][35][36][37] Here, the construction of the net can be done by taking into account the initial geometrical data as well as the chemically relevant interactions. [38,39] With this in mind, in an attemptt oc orrelate the different frameworks with their electronic properties, we have performed ac onscious supramolecular and topological analysis of the CdPF-n materials.…”

Untangling the Mechanochromic Properties of Benzothiadiazole-Based Luminescent Polymorphs through Supramolecular Organic Framework Topology

“…A number of metal complexes and purely organic compounds have been found to exhibit this interesting phenomenon; − however, only in a few of them is the underlying mechanism properly understood, despite the obvious importance of such knowledge in the development of new mechanochromic compounds. In this context, the emission switching between polymorphs is especially interesting. − By allowing the understanding of how molecules are self-associated in the solid state through a deep supramolecular analysis, we can use single crystals to help us realize how intermolecular interactions operate among each other, either separately or cooperatively, thus providing accurate information on the key factors that govern the correspondig solid-state light-emitting properties. ,− Unfortunately, although several mechanochromic luminophores have been reported to date, in most examples crystal-to-amorphous transitions originate in the differences of color observed.…”