Reversible On–Off Switching of Excitation-Wavelength-Dependent Emission of a Phosphorescent Soft Salt Based on Platinum(II) Complexes

Abstract

Excitation-wavelength-dependent (Ex-De) emission materials show excellent potential in diverse advanced photonic areas. Of significant importance is the on-demand regulation of the Ex-De luminescence behavior of these materials, which is previously unprecedented. In this study, we report on a platinum(II) complex-based phosphorescent soft salt S1 ([Pt(tpp)(ed)] + -[Pt(ftpp)(CN) 2 ] − (where ttp = 2-(4-(trifluoromethyl)phenyl)pyridine, ed = ethane-1,2-diamine, and ftpp = 2-(4-fluoro-3-(trifluoromethyl)phenyl)pyridine)) with Ex-De photoluminescence (PL) property. UV−visible absorption and PL spectra of S1 were recorded in DMSO−H 2 O mixture (1 × 10 −3 M) with various H 2 O fractions to investigate its ground and excited states. Interestingly, the PL spectra of S1 powder show that its maximum emission peak is red-shifted from 595 to 644 nm upon excitation at different wavelengths from 360 to 520 nm, accompanied by an obvious emission color change from yellow-orange to red. Furthermore, confocal laser scanning fluorescence microscopy was employed to determine the PL property of self-assembled uniform S1 nanostructure, and the result shows that the Ex-De emission behavior is absent. On the basis of these results, we conclude the various Pt(II)•••Pt(II) distances that exist are the major factor responsible for the properties of the Ex-De PL of S1 powder. Thus, for the first time, reversible on−off switching of Ex-De PL of S1 was achieved by manipulating its Pt(II)•••Pt(II) distances through mechanical stress and vapor fuming. Finally, we demonstrate the high-level anticounterfeiting applications via on-demand multicolor displays.

Excitation‐Dependent Emission in All‐Inorganic Lead‐Free Cs2ScCl5·H2O Perovskite Crystals

“…Materials with excitation-dependent emission have gained considerable attention due to their potential applications in encrypted information storage, multicolor display, and anticounterfeiting fields. [1][2][3][4][5][6][7] Their emission colors can be tuned simply by adjusting excitation wavelengths, without changing their size DOI: 10.1002/lpor.202100689 or chemical composition. The excitationdependent emission has been observed in metal complexes, [4,8] small molecules, [5,6] polymers, [9] and carbonbased semiconductors.…”

“…[1][2][3][4][5][6][7] Their emission colors can be tuned simply by adjusting excitation wavelengths, without changing their size DOI: 10.1002/lpor.202100689 or chemical composition. The excitationdependent emission has been observed in metal complexes, [4,8] small molecules, [5,6] polymers, [9] and carbonbased semiconductors. [10,11] Compared with the successful developments in construction of multiple emitting centers in organic materials, the research on singlecomponent inorganic semiconductors with excitation dependent emission is still in infancy.…”

Interface Engineering of Bi‐Fluorescence Molecules for High‐Performance Data Encryption and Ultralow UV‐Light Detection

“…Organic emitters with the dynamic ability to tune emission colors from different excited states in response to external stimuli, such as optical excitation, mechanical force, and pressure exhibit high potential in life science, energy conversion, and safety engineering. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] However, it is extremely difficult, selectively excited (Figure 1b). By varying the excitation energies from 4.27 eV (290 nm) to 3.44 eV (360 nm), the emission color of the OA-DFBK composites was deterministically tuned from deep blue to green in the spectral range.…”

“…Organic emitters with the dynamic ability to tune emission colors from different excited states in response to external stimuli, such as optical excitation, mechanical force, and pressure exhibit high potential in life science, energy conversion, and safety engineering. [ 1–16 ] However, it is extremely difficult, if not impossible, to achieve such a tunability due to the difficulty in separating large energies and the stability of different electronic excited states. [ 17–21 ] Therefore, it remains a challenge to precisely control the luminescence of organic chromophores from different electronically‐excited states.…”

Excitation‐Dependent Circularly Polarized Luminescence from Helical Assemblies Based on Tartaric Acid‐Derived Acylhydrazones

“…The first one is the selective excitation of different species in the ground state in a mixed system. This strategy is frequently actualized in systems composed of quantum dots, [4] metal complexes, [3b, 5] clusters [6] and polymers, [7] in which the emission color changes continuously with the excitation wavelength in a broad spectral range. The second capitalizes on the modulation between multiple emission pathways through regulating the relaxation channels, [8] which paves an appealing avenue to fabricating ExD materials based on small molecules and ensures high stability as well as precise tunability [9] .…”