Luminescent organic radicals, especially those with photoactivated circularly polarized luminescence (CPL) features, hold great significance for cutting-edge optoelectronic applications, but their development still remains a challenge. In this study, we propose a novel strategy to achieve photoactivated CPL radicals by bonding two phosphine centers within an axial chiral system, yielding a compound of R/S -5,5-bis(diphenylphosphino)-4,4′-bibenzo[d][1,3]dioxole ( R/S -BDP). The photoactivated R/S -BDP molecules in polymer matrix display a robust quantum yield of 19.8 % and a dissymmetry factor (g lum ) of 1.2×10 −4 , marking this work as the first example of photoactivated CPL radicals. Furthermore, the g lum is improved to 1.0×10 −2 by using a liquid crystal as host. Experimental and theoretical analyses reveal that R/S -BDP molecules, endowed with double phosphine cores in axial chirality, offer a direct way for intramolecular electron transfer upon photoirradiation. This leads to the generation of radical ionic pairs, which subsequently trigger the donor-acceptor arrangement through intermolecular electron transfer, thereby resulting in stable radical emission. The extended photoactivated BDP-F exhibits a remarkably high quantum efficiency of 57.8%. Ultimately, the distinctive photo-responsive CPL radical luminescence has been successfully used for information displays and anti-counterfeiting.

Photo-responsive metal complexes, which connect certain photo-switches with the distinctive metal ions, have aroused extensive interest in the fields of optoelectronic functional applications. Upon photoisomerization, these metal complexes exhibit dynamically tunable photophysical properties in terms of their absorption ability and range, emission color and intensity, photoisomerization rate, mechanical property, and so on. This review will provide an overview of the recent advances in photo-responsive metal complexes, including small molecules, metal-based macrocycles and supramolecular polymers. Moreover, the responsive mechanisms and design strategies, along with the applications of these photo-responsive metal complexes in optoelectronic devices are also discussed. Finally, the challenges and perspectives on future synthesis and extensive applications of photo-responsive metal complexes are also presented. This review shall offer important guidelines for designing novel photo-responsive metal complexes with controllable responsive behaviors for advanced optoelectronic applications.

Organic polymer photocatalysts have achieved significant progress in photocatalytic hydrogen evolution, while developing the integrated organic polymers possessing the functions of photosensitizer, electron transfer mediator, and catalyst simultaneously is urgently needed and presents a great challenge. Considering that chalcogenoviologens are able to act as photosensitizers and electron-transfer mediators, a series of chalcogenoviologen-containing platinum(II)-based supramolecular polymers is designed, which exhibited strong visible light-absorbing ability and suitable bandgap for highly efficient photocatalytic hydrogen evolution without the use of a cocatalyst. The hydrogen evolution rate (HER) increases steadily with the decrease in an optical gap of the polymer. Among these "all-in-one" polymers, Se-containing 2D porous polymer exhibited the best photocatalytic performance with a HER of 3.09 mmol g-1 h-1 under visible light (>420 nm) irradiation. Experimental and theoretical calculations reveal that the distinct intramolecular charge transfer characteristics and heteroatom N in terpyridine unit promote charge separation and transfer within the molecules. This work could provide new insights into the design of metallo-supramolecular polymers with finely tuned components for photocatalytic hydrogen evolution from water.

Phosphorescent manganese(II) complexes with high photoluminescence quantum yields (PLQYs) and low cost exhibit great potential in organic light-emitting diodes (OLEDs), information security, and X-ray imaging. However, it is still a challenge to tune their emission colors. Herein, an effective strategy for engineering the phosphorescence colors of tetrahedral Mn(II) complexes through steric hindrance-driven bond angle distortion is proposed. Modulating the steric hindrance between phosphine and benzofuran and varying the OMnO bond angles allows these Mn(II) complexes to emit from 498 to 548 nm. Interestingly, these achiral single crystals of Mn(II) complexes exhibit significant circularly polarized luminescence signals due to symmetry breaking. Furthermore, high-performance green OLEDs are achieved by using these Mn(II) complexes as dopants, providing a record-high external quantum efficiency of 15.7%. These super-duper results greatly inspire the development of multi-color Mn(II) complexes and low-cost Mn-based devices. An effective strategy to engineer the phosphorescence colors of tetrahedral neutral Mn(II) complexes is presented. These phosphorescent Mn(II) complexes exhibit wide color tunability from blue-green, green to yellow-green. Furthermore, by using these Mn(II) complexes as dopants, high-performance green organic light-emitting diodes (OLEDs) with a record-breaking external quantum efficiency of 15.7% are achieved.image

An aromatic moiety-free strategy is proposed for the excited state manipulation of a neutral manganese( ii ) halide scintillator towards efficient X-ray imaging with high spatial resolution of 11.3 lp mm −1 and low detection limit of 34.95 nGy s −1 .

Organic persistent room-temperature phosphorescence (RTP) polymers with exceptional processability, flexibility, and reproducibility exhibit great potential in various optoelectronic applications. However, it is still a challenge to achieve full-color RTP. In this study, we present a novel strategy for achieving multi-color phosphorescence in amorphous polymers by controlling the intermolecular electronic coupling among triphenylphosphine salts in a polyvinyl alcohol matrix. Notably, tunable phosphorescence colors ranging from deep blue to red are achieved. Both experimental and theoretical results have demonstrated that the inter-molecular electronic coupling among doping molecules is indeed responsible for wide-range room-temperature phosphorescence color tuning. Furthermore, these polymers have been successfully utilized in multi-color displays, including flexible three-dimensional objects and anti-counter-feiting tags.

Single molecules with dual persistent luminescence are very rarely explored, in spite of their emerging use in frontier optoelectronic applications. Here, a pure organic phosphor of tris(4‐chlorophenyl)phosphine oxide (CPO) possessing a large energy gap between the lowest excited triplet (T1) and higher excited triplet (T2) states is reported, which can emit dual persistent room‐temperature phosphorescence (RTP) from low‐ and high‐lying triplet excited states. The femtosecond transient absorption experiments and theoretical calculations reveal that the excitons to the T1 and T2 states are populated through different pathways. As a result, the distribution of the triplet excitons can be efficiently manipulated by using different excitation energy, and tunable afterglow colors from green to yellow can be achieved. Furthermore, the CPO molecule is successfully applied in the fabrication of high‐level anti‐counterfeiting tags and flexible 3D objects with curling properties. From these initial discoveries, it is expected that triphenylphosphine derivatives, with their rich chemistry of core‐substitution, can provide infinite opportunities in the expansion of organic molecules with high‐lying persistent RTP.

Three novel neutral manganese(ii) complexes (TPhPONMe2)2MnBr2, (TPhPOOMe)2MnBr2, and (TPhPOCF3)2MnBr2 have been designed and synthesized based on a functionalized Ph3PO ligand. These structures are clarified by single crystal X-ray diffraction analysis, which reveals that they crystallize in centrosymmetric space groups and feature an isolated mononuclear structure with Mn2+ in a tetrahedral environment. The photoluminescence spectra and emission lifetime decay curves of three manganese(ii) complexes show distinct green emission (λem = 498-512 nm) and phosphorescence lifetime (τ = 362.0-663.0 μs). The results of DFT calculations indicate that the energy levels of (TPhPONMe2)2MnBr2 and (TPhPOOMe)2MnBr2 are higher than that of (TPhPOCF3)2MnBr2 due to the electron-donating effect of the NMe2 or OMe group, which explains the blue-shift of the emission wavelength and the increase of emission lifetime. Furthermore, the prepared neutral manganese(ii) complexes can be used for high-resolution luminescent printing.

Organic persistent room-temperature phosphorescent (RTP) materials are promising for applications requiring the secure recording and anti-counterfeiting features owing to their appealing optical properties. Several critical challenges, such as the difficulty to obtain high-quality patterns over large areas and low security levels, need to be addressed to meet the requirements for commercial purpose. Here, we prepared a series of quaternary phosphonium salts with different alkyl chains, which showed interesting organic persistent RTP. The ionic characteristics and the alkyl chains of these molecules impart abundant weak intermolecular interactions. This confers the molecules a high crystallinity, which helps to preserve the persistent RTP properties and cover large areas. Moreover, the RTP lifetime of these organic salts varies over a wide range (1.27 to 884.71 ms) and can be tuned by simply changing the alkyl chain length and counterions, which opens new possibilities in multi-level information encryption applications. It is believed that the engineering of organic salts with tunable persistent RTP lifetimes and large-area printing can promote early-stage demonstrations of security applications into mature commercialization.

Recently, smart 2D covalent organic frameworks (COFs), combining the advantages of both inherent structure features and functional building blocks, have been demonstrated to show reversible changes in conformation, color, and luminescence in response to external stimuli. This review provides a summary on the recent progress of 2D COFs that are responsive to external stimuli such as metal ions, gas molecules, pH values, temperature, electricity, light, etc. Moreover, the responsive mechanisms and design strategies, along with the applications of these stimulus-responsive 2D COFs in chemical sensors and photoelectronic devices are also discussed. It is believed that this review would provide some guidelines for designing novel single-/multistimulus-responsive 2D COFs with controllable responsive behaviors for advanced photoelectronic applications.

Abstract Organic‐ligand‐containing frameworks have drawn considerable attention due to their multifunctional properties as well as tunable structures for broad applications. Among numerous synthesis methods developed in the past two decades, electrochemical processing has been demonstrated as one of the most efficient, safe, and facile ways to realize the large‐scale and highly controllable production of organic‐ligand‐containing frameworks. In this review, the progress of electrochemically induced crystallization and thin film fabrication of organic‐ligand‐containing frameworks is summarized in a well‐rounded way. Besides, the mechanism and processing parameters are also discussed. Moreover, the main challenges are also expounded for providing some guidance on the future development of organic‐ligand‐containing frameworks, especially for covalent‐organic frameworks and hydrogen‐bonded organic frameworks.

Organic luminophores exhibiting reversible changes in persistent room-temperature phosphorescence (RTP) upon exposure to external stimuli have shown great potential in diverse advanced photonic areas. Here, we present a molecular design strategy for the rational control of photoactivated persistent RTP behaviors of a series of triphenylphosphine oxide derivatives. By introducing various substituent groups, the responsive behaviors, such as photoactivation speeds and emission decay times upon UV excitation, are finely controlled. Crystal analyses and simulated calculations reveal that variations in molecular stacking upon photoirradiation are responsible for different persistent RTP behaviors. Also, one of the luminophores exhibits tunable persistent RTP from blue to green upon changing temperatures. Eventually, information encryption and visual temperature detection of these molecules are successfully demonstrated. Our study will pave the way for further development of novel stimuli-responsive persistent RTP materials with controllable responsive behavior for advanced photonic applications.

Materials exhibiting reversible changes in optical properties upon light irradiation have shown great potential in diverse optoelectronic areas. In particular, the modulation of photochromic behavior on demand for such materials is of fundamental importance, but it remains a formidable challenge. Here, we report a facile and effective strategy to engineer controllable photochromic properties by varying the counterions in a series of zinc complexes consisting of a spirolactam-based photochromic ligand. Colorability and coloration rate can be finely tuned by conveniently changing their counterions. Through utilization of the reversible feature of the metal-ligand coordination bond between Zn2+ and the spirolactam-based ligand, dynamic manipulation of photochromic behavior was achieved. Furthermore, we demonstrated the practical applications of the tunable photochromic properties for these complexes by creating photochromic films and developing multilevel security printing. These findings show opportunities for the development of smart materials with dynamically controllable responsive behavior in advanced optoelectronic applications.

Luminescent manganese(II) complexes have been extensively studied owing to their excellent photophysical properties. The facile synthesis and tunable optoelectronic performance of manganese(II) complexes render them attractive candidates for developing low-cost organic light-emitting diodes, information storage and security, as well as opto-electronic switches. In this review, we focus on the material category and synthesis, lumines Diverse optoelectronic applications of luminescent manganese complex are cence process, and various luminescent properties of manganese(II) complexes, together with their applications in functional devices. Finally, the challenge and outlook on the future research for manganese(II) complexes are given. (C) 2020 Elsevier B.V. All rights reserved.

Triboluminescence is a fascinating luminescence phenomenon induced by mechanical stimuli. Triboluminescent materials have potential applications in lighting, displays, and sensing, owing to their distinctive modes of light generation. However, organic triboluminescent materials are severely limited, and their luminescence mechanism remains unclear. Herein, we found that the luminescent manganese(II) complex [BPP](2)[MnBr4] displayed interesting triboluminescence performance. A series of green emissive tetrahalomanganese(II) complexes was rationally designed and synthesized. The associated single crystal structures revealed that all complexes consisted of one [MnX4](2-) (X = Br or Cl) ion and two organic cationic ligands per unit cell, with a tetrahedral geometrical symmetry around the Mn(II) ion. In addition, the photophysical properties of tetrahalomanganese(II) complexes were easily tuned by varying the organic ligands or halogen ions, which is beneficial for these organic-inorganic hybrid structures. Under UV light irradiation, all tetrahalomanganese(II) complexes in the solid state exhibited bright green luminescence and a broad featureless emission band at 450-650 nm. The time-resolved photoluminescent decay curves demonstrated that the emission lifetimes of the prepared tetrahalomanganese(II) complexes ranged from 260.5 mu s to 1.95 ms, which was attributed to phosphorescence. The long-lived emission was mainly due to the spin-forbidden nature of the metal center d-d (T-4(1)(G)-> (6)A(1)) radiative transition. Thermogravimetric analysis was performed to examine the thermodynamic stabilities of the tetrahalomanganese(II) complexes. The thermal stabilities of manganese(II) complexes with P-based ligands were higher than those of the complexes containing N-based ligands. Upon applying a force to the crystals, the tetrahalomanganese(II) complexes all exhibited prominent triboluminescence that could be observed by the naked eye in the dark. Systematic analysis of the crystals showed that the TL activities of the manganese(II) complexes were related to the intra- and inter-molecular C-H center dot center dot center dot X (X = Br or Cl) interactions. The intra- and inter-molecular C-H center dot center dot center dot X interactions significantly reduced the possible energy loss caused by molecular vibrations and rotations in the [MnX4](2-) unit under mechanical stress, improving TL emission. Moreover, a comparison of photoluminescence and triboluminescence indicated that different excitation sources yielded two distinct luminescence processes: transition of excitons excited by illumination and recombination of electrons and holes on the surface driven by polarization charges. Overall, the results presented herein new opportunities for fundamental research based on the developed class of triboluminescent materials.

Materials exhibiting reversible changes of their photoluminescence properties upon exposure to heat have an immense potential in various advanced photonic applications. Particularly, the control over an on‐demand response of thermochromic luminescent materials (TLMs) similar to a chameleon is of great importance. However, it is still difficult and challenging to achieve it. Therefore, this paper reports a simple and effective way to construct TLMs, which involves the incorporation of the metal–ligand complexes into polyethylene glycol (PEG). Ratiometric or off–on response modes of these TLMs can be tuned by incorporating metal complexes based on either Zn 2+ or Co 2+ into PEG and by taking advantage of reversible metal–ligand coordination, dissociation, or excited‐state conformation changes of the resulting materials. Moreover, by choosing PEG matrices with different molecular weights, the thermochromic transition temperatures of these TLMs can be tuned. It is also demonstrated that the controllable response behavior of these chameleon‐like TLMs can be used in applications related to real‐life anti‐counterfeiting and security printing. This work opens novel opportunities for the development of smart materials with controllable responses useful for advanced photonic applications.

Pure organic materials with tunable room temperature phosphorescence (RTP) have attracted considerable interest because they are promising candidates for a wide range of optoelectronic applications. Herein, a series of organic compounds of (4-(9H-carbazol-9-yl)butyl) triphenylphosphonium (CBTP) with different halide anions (CBTP-Cl, CBTP-Br, and CBTP-I) are synthesized. They show emission color changes from blue to orange-red in the solid state. Single-crystal X-ray diffraction analysis and theoretical calculations demonstrate that the RTP is primarily caused by the external heavy-atom effect (EHE), which enhances the spin-orbit coupling between the singlet and triplet excited states to facilitate the intersystem crossing rate. Distinct white light emission can be achieved using the controllable RTP by doping a certain ratio of potassium iodide (KI) into a polymer matrix containing CBTP-Cl. Moreover, luminescent information can be recorded on a paper substrate made from a polymer film containing CBTP-Cl with KI aqueous solution as the ink. The results suggest that rational control of the EHE of these pure organic materials is promising for different optoelectronic applications, including solid-state lighting, data recording, and security protection.

Application of external stimuli in self-assembly processes would offer greater degrees of freedom to regulate the supramolecular nanostructures and functions of self-assembling molecules. In particular, the utilization of electric field to control molecular self-assembly is of fundamental significance, and it contributes to the development of applications in nanofabrication and optoelectronic fields. Here, the self-assembly of an anionic platinum complex ([Pt(tfmpy)(CN)(2)]-Bu4N+, tfmpy = 2-(4-(trifluoromethyl)phenyl)pyridine) is studied in the absence or presence of an electric field. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate an interesting morphological transformation from rod-like to flower-shaped nanoaggregate structures. For rod-like nanostructure, selected area electron diffraction (SAED) and powder X-ray diffraction (PXRD) analysis suggest that the Bu4N+ cations are squeezed between adjacent platinum(II) complex anions, forming alternating layers of two ions. In addition, SAED result suggests that the flower-shaped nanoaggregate is constructed by a layer-by-layer packing through the formation of Pt center dot center dot center dot Pt and pi-pi stacking interactions. Importantly, confocal fluorescence imaging shows that these two different stable assemblies possess distinct emission colors and lifetimes. This unique feature might be useful in various optoelectronic applications including data recording, anti-counterfeiting, smart windows, etc.