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

Abstract

Two new luminophore polymorphs of 4-bromo-7-(4nonylphenyl)benzo [c][1,2,5]thiadiazole (1α and 1β) exhibiting different color emissions, which switch into each other in response to shear force and solvent vapors, are presented and their X-ray structure is determined. Supramolecular organic framework topology (SOFT) studies on the two polymorphic structures led us to conclude that the mechanochromic phase transformation can be explained on the basis of modifications in their respective topological nets: mab and pcu for 1α and 1β, respectively, as a result of the breaking and restoration of a number of weak supramolecular interactions. The color changes accompanying this transformation have been rationalized with the help of time-dependent density functional theory. We firmly believe that our findings will inspire future research on the design of novel stimuli-responsive organic materials with switchable properties based on their supramolecular interactions by establishing clear SOFT-property relationships.

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.…”

A high contrast mechanochromic luminescent diacetylene-linked bis-benzothiadiazole derivative

“…The synthesis of the dimeric compounds 4 and 5 was performed starting from 4-bromo-7-(4-nonylphenyl)benzo[c][1,2,5]thiadiazole 2 which can be readily obtained starting from commercial 4,7-dibromobenzo[c][1,2,5]thiadiazole 2 through Suzuki coupling with one equivalent of 4-nonylphenylboronic acid as has been previously reported. 22 Self-coupling reaction of 2 catalysed by Pd(OAc) 2 in polyethylene glycol (PEG4000), 29,30 rendered straightforwardly compound 4 in good yield (Scheme 1). Compound 5 was obtained by Cu-catalysed oxidative Eglinton coupling of the corresponding ethynyl derivative 3, which is readily accessed in two steps by Sonogashira coupling of 2 with ethynyl trimethylsilane, followed by deprotection with KF (Scheme 1).…”

“…In the quest for new organic stimuli responsive materials, the 2,1,3-benzothiadiazole moiety (BTD) have emerged as a promising building block, as the absorption and emission properties of its derivatives are strongly influenced by their external environment. 20,21 In the last few years several BTDbased chromogenic and fluorogenic materials have been reported, but although there are some recent exceptions, 19,22,23 in most examples crystalline-to-amorphous transitions are in the origin of this behaviour. 20,[24][25][26][27][28] This fact prevents an in-depth understanding of the mechanism behind the different optical properties observed.…”

Development of Dual Phosphorescent Materials Based on Multiple Stimuli-Responsive Ir(III) Acyclic Carbene Complexes

“…Mechanoresponsive and multiple stimuli-responsive luminescent compounds, which can change their luminescent properties by external stimuli, including mechanical force, magnetic field, temperature, light, and chemical vapors, have important applications as luminescent smart materials. [1][2][3][4][5][6][7][8][9] These stimuli-responsive behaviors can be derived from intermolecular and/or intramolecular processes. [10][11][12] To date, most of the reported mechanoresponsive systems are mainly developed from the changes of intermolecular interactions such as π-π, hydrogen, dipole-dipole, metal-metal, and metal-ligand interactions associated with a crystalline to amorphous transition [13][14][15][16][17][18][19][20][21][22][23][24] or a change of the aggregation state.…”