Realization of Distinct Mechano- and Piezochromic Behaviors via Alkoxy Chain Length-Modulated Phosphorescent Properties and Multidimensional Self-Assembly Structures of Dinuclear Platinum(II) Complexes

Abstract

In this work, through the introduction of different lengths of alkoxy chains to the dinuclear cyclometalated platinum­(II) complexes, the apparent color, solubility, luminescence properties, and self-assembly behaviors have been remarkably modulated. In the solid state, the luminescence properties have been found to arise from emission origins that switch between the 3MMLCT excited state in the red solids and the 3IL excited state in the yellow state, depending on the alkoxy chain lengths. The luminescence of the yellow solids is found to show obvious bathochromic shifts under mechanical grinding and decreased intensity under controllable hydrostatic pressure. However, the emission of the red solids exhibits both a bathochromic shift and reduced intensity due to the isotropic compression-induced shortening of the Pt···Pt and π–π distances. By combining the data obtained from X-ray diffraction (XRD), infrared (IR), and X-ray single crystal structure, a better understanding of the relationship between molecular aggregation and photophysical properties has been realized, suggesting that the length of the alkoxy chains plays an important role in governing the supramolecular assemblies.

Mechanofluorochromism of (D–π–)2A-type azine-based fluorescent dyes

“…In particular, the intermolecular MFC (inter-MFC) based on reversible changes in molecular orientation and arrangement of dye molecules is superior in durability to the intramolecular MFC (intra-MFC) based on reversible changes in the chemical structures of dye molecules by cleavage and reconstruction of chemical bonds during the grinding–heating process, and thus, the inter-MFC is expected to be applicable to rewritable photoimaging and electroluminescence devices. 8–70 Among various types of fluorescent dyes possessing the mechanofluorochromic properties, donor–π–acceptor (D–π–A)-type fluorescent dyes composed of an electron-donating moiety (D) and an electron-withdrawing moiety (A) connected by a π-conjugated bridge exhibit intense photoabsorption and fluorescence emission properties based on the intramolecular charge transfer (ICT) excitation from the D moiety to the A moiety. 11–33 Thus, the dipole moments as well as photoabsorption ( i.e.…”

Construction of Mechanofluorochromic and Aggregation‐Induced Emission Materials Based on 4‐Substituted Isoquinoline Derivatives

“…Organic mechanofluorochromic (MFC) materials are a kind of important smart fluorescence materials, which exhibit the changes of fluorescent colors under the stimulation of external pressure, have received extensive attention due to the application in solid-state fluorescent sensors, anti-counterfeiting materials, and optical recording. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] In early studies, the discovery of such materials was mostly based on chance, [1] in fact, although many organic MFC materials have been reported till now, the design strategy and formation mechanism are still unclear. Generally speaking, it is believed that an organic molecule with twisted molecular conformation and capable of emitting solid-state fluorescence is a potential candidate for MFC molecules, because the twisted conformation is easy to lead to loose stacking mode and thus a morphological change under the stimulation of external pressure, resulting in the change of solid-state fluorescence color.…”

“…Organic mechanofluorochromic (MFC) materials are a kind of important smart fluorescence materials, which exhibit the changes of fluorescent colors under the stimulation of external pressure, have received extensive attention due to the application in solid‐state fluorescent sensors, anti‐counterfeiting materials, and optical recording [1–15] . In early studies, the discovery of such materials was mostly based on chance, [1] in fact, although many organic MFC materials have been reported till now, the design strategy and formation mechanism are still unclear.…”

Single‐Crystal‐to‐Single‐Crystal Transformation and Alcohols Enantioseparation of Homochiral Ir(III)‐Metallohelix‐Based Porous Molecular Crystal

“…[10][11][12][13] Noted that current researches on SCSC transformations primarily concentrated on classical extended networks, such as metalorganic frameworks (MOFs) and covalent organic frameworks (COFs). [14][15][16][17][18][19] Although various external stimuli, such as solvent, template molecules, light, temperature, or post-modification reactions, could successfully trigger SCSC transformations, [20][21][22][23][24][25][26] as a matter of fact, preservation of crystallinity is still challenging due to the framework is easy to collapse irreversibly and even disintegrate into pieces during the transformations process. [27][28] On the other hand, as a new class of functional porous solids, porous molecular crystals, which are composed of discrete organic or metal-organic cage modules, have got growing interest in various fields from supramolecular chemistry to materials science.…”