Photophysical Tuning of Organic Ionic Crystals from Ultralong Afterglow to Highly Efficient Phosphorescence by Variation of Halides

Abstract

Manipulation of photophysical properties of pure organic materials via simple alteration is attractive but extremely challenging because of the lack of valid design strategies for achieving ultralong afterglow or efficient room-temperature phosphorescence. Herein, we report a first photophysical manipulation of organic ionic crystals from ultralong afterglow to highly efficient phosphorescence by variation of halides in the crystals. Crystal structural analysis reveals ultralong organic afterglow of tetraphenylphosphonium chloride is promoted by strong intermolecular electronic coupling in the crystal, and theoretical analysis demonstrates that the tremendous boost of the phosphorescence of tetraphenylphosphonium iodide is caused by the coupling effects of significant heavy atom effect from iodine atoms and a small energy difference between the first singlet and triplet states. This work contributes to regulating long-lived emissive behaviors of pure organic ionic crystals in a controlled way and will promote the development of optical switches controlled by external stimuli.

Manipulating the Ultralong Organic Phosphorescence of Small Molecular Crystals

“…discussed the effect of different halogens on the electronic properties of molecules and clearly proposed that the HOMO–LUMO gap could be reduced by functionalization with Cl, Br, and I. Recently, many strategies to improve the efficiency of UOP have been proposed involving introducing halogen heavy atoms, such as introducing the chromophore into a host matrix, enhancing heavy atom cluster interactions in single‐component crystals (molecules 44 – 47 ), and introducing halogen anions into ionic crystals (molecules 48 – 51 ), and so on. However, intermolecular noncovalent bonding often leads to unpredictable molecular packing, making it noncontrollable.…”

Magnesium Klorida (MgCl2): Karakteristik dan Dinamika Molekuler Pada MgCl2

“…Cl Magnesium klorida adalah nama senyawa kimia dengan rumus MgCl 2 dan berbagai hidratnya MgCl2 (H2O) x. Magnesium klorida ini adalah garam dalam halida ionik (132)(133)(134) yang khas, sangat mudah larut dalam air. MgCl2 anhidrat adalah asam Lewis, walaupun bersifat sangat lemah.…”

Ultralong room-temperature phosphorescence of a solid-state supramolecule between phenylmethylpyridinium and cucurbit[6]uril

“…However, achieving ultralong RTP (generally from seconds to hours) is extremely difficult due to two main issues: (i) the intrinsically weak spin-orbit coupling of purely organic molecules makes it hard to achieve efficient intersystem crossing (ISC); (ii) a long triplet state (T 1 ) lifetime means that T 1 will suffer tremendously from quenching by a very low concentration of impurities even in crystals. 6 Several methods have been reported to actualize long-lived RTP, such as forming charge-separated states, 7 crystallization, [8][9][10][11][12][13][14][15][16][17] polymerization, [18][19][20][21] embedding into suitable matrices, [22][23][24] and so on. [25][26][27] Recently, Huang and co-workers achieved lifetimes of 1.35 s and 1.91 s by reasonable crystal design.…”