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An unprecedented fully reduced {MoV60} POM served as a cheap and robust molecular light-absorber model possessing wide light absorption and was applied to build a co-sensitized solar cell photoelectronic device.

Switchable multimode microlasers are of great significance to the development of photonic devices with high integration levels. Herein, we demonstrate an acid/alkaline gas-responsive multimode AIEgen@starch microsphere-based microlaser. The aggregation-induced emission (AIE) active fluorescent dye ASCPI was used as the gain medium in this study. ASCPI was weakly emissive in water but became highly emissive when introduced to a starch microsphere as a guest molecule. The resultant ASCPI@starch microsphere worked well as a typical whispering-gallery-mode microlaser. The laser mode wavelengths were size-dependent. Due to the sensitivity of ASCPI to pH, the output of the microlaser could be switched to a shorter wavelength by acetic acid vapor treatment or a longer wavelength by NH3 vapor treatment. This work will provide useful enlightenment for the rational design of effective switchable lasers using AIE materials with simple preparation procedures.

Visually identifying pathogens favors rapid diagnosis at the point-of-care testing level. Here, we developed a microenvironment-sensitive aggregation-induced emission luminogen (AIEgen), namely IQ–Cm, for achieving fast discrimination of Gram-negative bacteria, Gram-positive bacteria and fungi by the naked-eye. With a twisted donor–acceptor and multi-rotor structure, IQ–Cm shows twisted intramolecular charge transfer (TICT) and AIE properties with sensitive fluorescence color response to the microenvironment of pathogens. Driven by the intrinsic structural differences of pathogens, IQ–Cm with a cationic isoquinolinium moiety and a membrane-active coumarin unit as the targeting and interacting groups selectively locates in different sites of three pathogens and gives three naked-eye discernible emission colors. Gram-negative bacteria are weak pink, Gram-positive bacteria are orange-red and fungi are bright yellow. Therefore, based on their distinctive fluorescence response, IQ–Cm can directly discriminate the three pathogens at the cell level under a fluorescence microscope. Furthermore, we demonstrated the feasibility of IQ–Cm as a visual probe for fast diagnosis of urinary tract infections, timely monitoring of hospital-acquired infection processes and fast detection of molds in the food field. This simple visualization strategy based on one single AIEgen provides a promising platform for rapid pathogen detection and point-of-care diagnosis., A simple AIEgen with three emission colors achieves rapid identification of Gram-negative bacteria, Gram-positive bacteria and fungi.

Fully reduced polyoxometalates are predicted to give rise to a broad and strong absorption spectrum, suitable energy levels, and unparalleled electronic and optical properties. However, they are not available to date. Here, an unprecedented fully reduced polyoxomolybdate cluster, namely Na

Antibacterial photodynamic therapy (PDT) is one of the emerging methods for curbing multidrug-resistant bacterial infections. Effective fluorescent photosensitizers with dual functions of bacteria imaging and PDT applications are highly desirable. In this study, three cationic and heteroleptic cyclometalated Ir(III) complexes with the formula of [Ir(CˆN)2 (NˆN)][PF6 ] are prepared and characterized. These Ir(III) complexes named Ir(ppy)2 bP, Ir(1-pq)2 bP, and Ir(2-pq)2 bP are comprised of three CˆN ligands (i.e., 2-phenylpyridine (ppy), 1-phenylisoquinoline (1-pq), and 2-phenylquinoline (2-pq)) and one NˆN bidentate co-ligand (bP). The photophysical characterizations demonstrate that these Ir(III) complexes are red-emitting, aggregation-induced emission active luminogens. The substitution of phenylpyridine with phenylquinoline isomers in the molecules greatly enhances their UV and visible-light absorbance as well as the photoinduced reactive oxygen species (ROS) generation ability. All three Ir(III) complexes can stain both Gram-positive and Gram-negative bacteria efficiently. Interestingly, even though Ir(1-pq)2 bP and Ir(2-pq)2 bP are constitutional isomers with very similar structures and similar ROS generation ability in buffer, the former eradicates bacteria much more effectively than the other through white light-irradiated photodynamic inactivation. This work will provide valuable information on the rational design of Ir(III) complexes for fluorescence imaging and efficient photodynamic inactivation of bacteria.

Photosensitizers (PSs) with multiple characteristics, including efficient singlet oxygen (1O2) generation, cancer cell-selective accumulation and subsequent mitochondrial localization as well as near-infrared (NIR) excitation and bright NIR emission, are promising candidates for imaging-guided photodynamic therapy (PDT) but rarely concerned. Herein, a simple rational strategy, namely modulation of donor–acceptor (D–A) strength, for molecular engineering of mitochondria-targeting aggregation-induced emission (AIE) PSs with desirable characteristics including highly improved 1O2 generation efficiency, NIR emission (736 nm), high specificity to mitochondria, good biocompatibility, high brightness and superior photostability is demonstrated. Impressively, upon light irradiation, the optimal NIR AIE PS (DCQu) can generate 1O2 with efficiency much higher than those of commercially available PSs. The excellent two-photon absorption properties of DCQu allow two-photon fluorescence imaging of mitochondria and subsequent two-photon excited PDT. DCQu can selectively differentiate cancer cells from normal cells without the aid of extra targeting ligands. Upon ultralow-power light irradiation at 4.2 mW cm−2, in situ mitochondrial photodynamic activation to specifically damage cancer cells and efficient in vivo melanoma ablation are demonstrated, suggesting superior potency of the AIE PS in imaging-guided PDT with minimal side effects, which is promising for future precision medicine., Mitochondria-targeted photosensitizers with highly efficient singlet oxygen generation, bright near-infrared AIE and good two-photon absorption are obtained through ingenious molecular engineering for cancer cell-selective photodynamic therapy.

Advanced 1.5-µm emitting materials that can be used to fabricate electrically driven light-emitting devices have the potential for developing cost-effective light sources for integrated silicon photonics. Sensitized erbium (Er3+) in organic materials can give bright 1.5-µm luminescence and provide a route for realizing 1.5-µm organic light emitting diodes (OLEDs). However, the Er3+ electroluminescence (EL) intensity needs to be further improved for device applications. Herein, an efficient 1.5-µm OLED made from a sensitized organic Er3+ co-doped system is realized, where a “traditional” organic phosphorescent molecule with minimal triplet–triplet annihilation is used as a chromophore sensitizer. The chromophore provides efficient sensitization to a co-doped organic Er3+ complex with a perfluorinated-ligand shell. The large volume can protect the Er3+ 1.5-µm luminescence from vibrational quenching. The average lifetime of the sensitized Er3+ 1.5-µm luminescence reaches ~0.86 ms, with a lifetime component of 2.65 ms, which is by far the longest Er3+ lifetime in a hydrogen-abundant organic environment and can even compete with that obtained in the fully fluorinated organic Er3+ system. The optimal sensitization enhances the Er3+ luminescence by a factor of 1600 even with a high concentration of the phosphorescent molecule, and bright 1.5-µm OLEDs are obtained., Light emission: Erbium and iridium make a powerful combination Light emission from ions of the element erbium, for use in electrically driven light-emitting devices, can be significantly enhanced by adding sensitizer materials containing iridium ions. The potential of erbium for cost-effective light emission in photonics applications is well-recognized, but methods to increase the power efficiency of the devices are keenly sought. Hong-Fei Li and colleagues at Queen Mary University of London, UK, and Northeast Normal University in Changchun, China, found that a phosphorescent iridium complex enhanced the emission from an erbium complex by a factor of up to 1600. The dramatic effect of the iridium sensitizer was demonstrated in an organic (carbon-based) light-emitting diode. This innovation emphasizes the potential advantages of exploring combinations of molecular complexes in light-emitting devices, rather than seeking a single light-emitting molecule possessing all of the properties required.

Luminescent sensors have received extensive attention due to their fast-response and easy-operation and when integrating multifunctions in a sensor, the cost will be reduced substantially. Covalent organic polymers (COPs) as multifunctional luminescent sensor with outstanding performance are still underexplored. In this work, a typical COP named as COP-2 show preponderant performance in the detection of Fe3+, MnO4−, and TNP. COP-2 has the highly efficient ability to selectively detect Fe3+ among the other metal ions, and the limit of the detection (LOD) is 0.89 ​μM, which outperforms the reported covalent organic materials. Anion sensing shows the COP-2 has the highly anti-interference ability and recyclicity to detect MnO4−. Explosive analogs sensing demonstrates that COP-2 owns the superior ability in sensing TNP in the knockdown concentration with 0.0067 ​ppm LOD, which superior to the values in the reported literature. In addition to the above superb sensing performance, COP-2 can be utilized as a white light-emitting diode (WLED) when combined with the commercial blue emission LED and presents a Commission Internationale de l’Eclairage (CIE) coordinate of (0.31, 0.32). These results show the COP-2 not only has an appealing performance in multifunctional luminescent sensing application, but also has a possible application in white light emitting.

A neutral dinuclear Ir(iii) Schiff base complex PIBIP has been synthesized and shown to exhibit both piezochromic luminescence (PCL) and aggregation induced emission (AIE) behaviour. An efficient second-level anti-counterfeit trademark and a data encryption device were fabricated using PIBIP as the active material.

Retraction of ‘Sublimable cationic Ir(iii) phosphor using chlorine as a counterion for high-performance monochromatic and white OLEDs’ by Lei Ding et al., Chem. Commun., 2018, 54, 11761–11764.

Efficient organic photosensitizers (PSs) have attracted much attention because of their promising applications in photodynamic therapy (PDT). However, guidelines on their molecular design are rarely reported. In this work, a series of PSs are designed and synthesized based on a triphenylamine-azafluorenone core. Their structure-property-application relationships are systematically studied. Cationization is an effective strategy to enhance the PDT efficiency of PSs by targeting mitochondria. From the molecularly dispersed state to the aggregate state, the fluorescence and the reactive oxygen species generation efficiency of PSs with aggregation-induced emission (AIE) increase due to the restriction of the intramolecular motions and enhancement of intersystem crossing. Cationized mitochondrion-targeting PSs show higher PDT efficiency than that of nonionized ones targeting lipid droplets. The ability of AIE PSs to kill cancer cells can be further enhanced by combination of PDT with radiotherapy. Such results should trigger research enthusiasm for designing and synthesizing AIE PSs with better PDT efficiency and properties.

Significant efficiency roll-off of phosphorescent organic light-emitting diodes (PHOLEDs) is a long-standing issue that limits their wider application. To address this problem, four iridium(III) complexes modified by methyl or tert-butyl groups were designed and synthesized, denoted as Me-Ir-PI, tBu-Ir-PI, Me-Ir-PB, and tBu-Ir-PB. Their photophysical, electrochemical, and electroluminescent properties were studied in detail. The electroluminescent performances of devices based on tBu-Ir-PI and tBu-Ir-PB were better than those based on Me-Ir-PI and Me-Ir-PB. The best performance was achieved by the doped device employing tBu-Ir-PI as the emitter with maximum current efficiency of 42.0 cd A−1 and maximum power efficiency of 27.0 lm W−1. Even at a practical brightness of 1000 cd m−2, the current efficiency and power efficiency remained as high as 39.2 cd A−1 and 22.3 lm W−1. Notably, all doped devices exhibited low efficiency roll-off, especially for device incorporation of tBu-Ir-PB as the guest emitter, which had extremely low roll-off of 0.9%. Meanwhile, non-doped devices based on these iridium(III) complexes also displayed good EL performances.

Research on materials with pure organic room temperature phosphorescence (RTP) and their application as organic single-molecule white light emitters is a hot area and relies on the design of highly efficient pure organic RTP luminogens. Herein, a facile strategy of heavy-atom-participated anion–π+ interactions is proposed to construct RTP-active organic salt compounds (1,2,3,4-tetraphenyloxazoliums with different counterions). Those compounds with heavy-atom counterions (bromide and iodide ions) exhibit outstanding RTP due to the external heavy atom effect via anion–π+ interactions, evidently supported by the single-crystal X-ray diffraction analysis and theoretical calculation. Their single-molecule white light emission is realized by tuning the degree of crystallization. Such white light emission also performs well in polymer matrices and their use in 3D printing is demonstrated by white light lampshades., The demonstration of pure organic room temperature phosphorescence (RTP) luminogens with complementary emission is a key requirement for developing low-cost white light emitters. Here, the authors construct RTP-active organic salt compounds by exchanging the counterion with a heavy halide ion.

Heterocyclic polymers have gained enormous attention for their unique functionalities and wide applications. In contrast with the well-studied polymer systems with five- or six-membered heterocycles, functional polymers with readily openable small-ring heterocycles have rarely been explored due to their large synthetic difficulty. Herein, a facile one-pot multicomponent polymerization to such polymers is developed. A series of functional polymers with multisubstituted and heteroatom-rich azetidine frameworks are efficiently generated at room temperature in high atom economy from handy monomers. The four-membered azetidine rings in the polymer skeletons can be easily transformed into amide and amidine moieties via a fast and efficient acid-mediated ring-opening reaction, producing brand-new polymeric materials with distinctive properties. All the as-prepared azetidine-containing polymers exhibit intrinsic visible luminescence in the solid state under long-wavelength UV irradiation even without conventionally conjugated structures. Such unconventional luminescence is attributed to the clusteroluminogens formed by through-space electronic interactions of heteroatoms and phenyl rings. All the obtained polymers show excellent optical transparency, high and tunable refractive indices, low optical dispersions and good photopatternability, which make them promising materials in various advanced electronic and optoelectronic devices. The ring-opened polymers can also function as a lysosome-specific fluorescent probe in biological imaging.

A pillar-layer MOFs Cd(5-aip)L·3DMA (1) has been obtained under solvothermal conditions. 1 possesses non-interpenetrating pillar-layer framework with 1D rectangular-shape channels. The experimental results show that the luminescent intensity of 1 is highly dependent on metal ions and small solvent molecules, particularly Ni2+/Cd2+ ions and acetone.

A density functional theory/time-depended density functional theory was used to investigate a series of heteroleptic Ir(III) complexes (1–4) employing azadipyrromethene and closely related dipyrromethene derivatives as N^N ancillary ligands, in an effort to explore the underlying reasons of non-radiative behaviour of 1 and further adjust the photophysical properties by the modification of N^N ancillary ligands. The results reveal that the non-emissive phenomenon of 1 can be attributed to the weak 3ILCT character of the emissive excited state and large structure distortion, as well as the small Topt1–Sopt0 energy gap. Upon tailoring the N^N ancillary ligands, the geometry distortion of 2–4 becomes obviously smaller in comparison with 1, accordingly, the spectrum properties are also markedly affected. For instance, the enlargement of frontier molecular orbital energy gaps from 1 to 4 results in the blue-shift of their absorption and emission spectra, which is considered to be dominated by the ancillary ligand, while there is a little contribution from the Ir(III) center. Importantly, further analysis on the quantum yield (ΦPL) of these complexes also indicates a vital role of N^N ancillary ligands. It is intriguing to note that the designed complex 4 without pendant phenyl rings substituent in the ancillary ligand, possesses an efficient indirect spin-orbital coupling route, larger transition electric dipole moment (μS3), higher Topt1–Sopt0 energy gap and smaller S3–T1 splitting energy (ΔE(S3–T1)), which ensure its higher ΦPL compared to other complexes.

The mechanism of thermally activated delayed fluorescence (TADF) in molecules in aggregated or condensed solid states has been rarely studied and is not well understood. Nevertheless, many applications of TADF emitters are strongly affected by their luminescence properties in the aggregated state. In this study, two new isomeric tetradentate Cu(I) complexes which simultaneously show aggregation induced emission (AIE) and TADF characteristics are reported for the first time. We provide direct evidence that effectively restricting the vibrations of individual molecules is a key requisite for TADF in these two Cu(I) complexes through in-depth photophysical measurements combined with kinetic methods, single crystal analysis and theoretical calculations. These findings should stimulate new molecular engineering endeavours in the design of AIE-TADF active materials with highly emissive aggregated states.

The syntheses of two new heteroleptic cationic iridium complexes containing 2,6-diphenylpyridine (Hdppy) and 2,4,6-triphenylpyridine (Htppy) as the cyclometalated ligands, namely, [Ir(dppy)2phen]PF6 (1, phen = 1,10-phenanthroline) and [Ir(tppy)2phen]PF6 (2), are described. The X-ray crystal structure of 2 reveals a distorted octahedral geometry around the Ir center and close intramolecular face-to-face π–π stacking interactions between the pendant phenyl rings at the 2-position of the cyclometalated ligands and the NN ancillary ligand. This represents a new π–π stacking mode in charged Ir complexes. Complexes 1 and 2 are green photoemitters: their photophysical and electrochemical properties are interpreted with the assistance of density functional theory (DFT) calculations. These calculations also establish that the observed intramolecular interactions cannot effectively prevent the lengthening of the Ir–N bonds of the complexes in their metal-centered (3MC) states. Complexes 1 and 2 do not emit light in light-emitting electrochemical cells (LECs) under conditions in which the model compound [Ir(ppy)2phen]PF6 (3) emits strongly. This is explained by degradation reactions of the 3MC state of 1 and 2 under the applied bias during LEC operation facilitated by the enhanced distortions in the geometry of the complexes. These observations have important implications for the future design of complexes for LEC applications.

Two heteroleptic iridium(III) complexes using carbene as cyclometalated ligands and pyridine-triazole as ancillary ligand, namely (fpmi)2Ir(mtzpy) (1) and (fpmi)2Ir(phtzpy) (2) [fpmi = 1-(4-fluorophenyl)-3-methylimdazolin-2-ylidene-C,C2′, mtzpy = 2-(5-methyl-2H-1,2,4-triazol-3-yl)pyridine, phtzpy = 2-(5-phenyl-2H-1,2,4-triazol-3-yl)pyridine], were synthesized and their structural, photophysical and electrochemical properties investigated systematically. Both complexes exhibit bright greenish-blue phosphorescence (λmax ∼490 nm) with quantum yields of about 0.50. Comprehensive density functional theory (DFT) approach was then performed to gain insights into their photophysical and electrochemical characters. The fabrication of organic light-emitting diodes (OLEDs), employing complexes 1 and 2 as phosphorescent dopants, was successfully achieved. Among them, the device based on 1 exhibited considerable power efficiency (ηp) of 11.43 lm W−1 and current efficiency (ηc) of 11.78 cd A−1. With the merit of intrinsic characteristic of complex 1, a white OLED comprised of 1 and one orange phosphor (pbi)2Ir(biq) achieved a peak ηp of 9.95 lm W−1 and ηc of 10.81 cd A−1, together with Commission Internationale de l'Eclairage (CIE) coordinates of (0.34, 0.40). The results indicate that two iridium(III) complexes reported here are promising phosphorescent dyes for OLEDs.

Solution-processable light-emitting electrochemical cells (LECs) with simple device architecture have become an attractive candidate for application in next generation lighting and flat-panel displays. Herein, single layer LECs employing two cationic Ir(III) complexes showing highly efficient blue-green and yellow electroluminescence with peak current efficiency of 31.6 cd A−1 and 40.6 cd A−1, respectively, have been reported. By using both complexes in the device, color-tunable LECs with a single spectral peak in the wavelength range from 499 to 570 nm were obtained by varying their rations. In addition, the fabrication of efficient LECs was demonstrated based on low cost doctor-blade coating technique, which was compatible with the roll to roll fabrication process for the large size production. In this work, for the first time, 4 inch LEC devices by doctor-blade coating were fabricated, which exhibit the efficiencies of 23.4 cd A−1 and 25.4 cd A−1 for the blue-green and yellow emission, respectively. The exciting results indicated that highly efficient LECs with controllable color could be realized and find practical application in large size lighting and displays.

A series of substituted phenanthroline ancillary ligands with different degrees of steric hindrance, namely, 4,7-di(1H-pyrrol-1-yl)-1,10-phenanthroline (L1), 4,7-di(1H-indol-1-yl)-1,10-phenanthroline ( L2 ) and 4,7-di(9H-carbazol-9-yl)-1,10-phenanthroline ( L3 ), were synthesized in order to prepare cationic Ir(III) complexes. The results of photophysical studies revealed that functionalization with higher degree of steric hindrance L3 led to significant improvement of photoluminescence quantum yields (PLQYs) in neat film for these Ir(III) complexes, which may be attributed to the decrease of the intermolecular interactions. The mechanism of photophysical properties were rationalized with the help of quantum chemical calculations. Moreover, the complexes with L3 as ancillary ligands possessed good thermal stability, indicating their potential application as candidate for light-emitting electrochemical cells (LECs).

Efficient aggregation induced phosphorescence emission (AIPE) of an ionic Ir(iii) complex occurs when the counterion (PF6(-)) is exchanged specifically by ClO4(-) in aqueous media. As a result, a rapid, highly selective "turn-on" phosphorescent response to ClO4(-) is observed in aqueous media. These studies pave the way for a new efficient phosphorescence-based detection strategy for anions.

Two new ionic dinuclear Ir(III) Schiff base complexes which are straightforward to synthesise have luminescence quantum yields as high as 37% in neat films. These are the first examples of dinuclear ionic Ir(III) complexes that display aggregation-induced phosphorescent emission (AIPE).

Metal–organic frameworks (MOFs) are well known for their tunable structure and porosity. Many studies have shown they are promising for various important applications, for which their performance can be further enhanced by encapsulating functional species, such as luminescent guest molecules, within the frameworks. Although numerous MOFs are luminescent, very few emit white light and their quantum yield is usually low. Here we report a strategy to achieve efficient white-light emission by encapsulating an iridium complex in the MOF cavity. A mesoporous blue-emitting MOF is prepared as host to encapsulate a yellow-emitting iridium complex, [Ir(ppy)2(bpy)]+. The resultant composites emit bright white light with good colour quality (for example, Commission International de I’Eclairage coordinates, colour-rendering index and correlated colour temperature of (0.31, 0.33), 84.5 and 5409 K, respectively), and high quantum yield up to 115 °C. This strategy may open new perspectives for developing high-performance energy-saving solid-state lighting materials., Although many metal–organic frameworks are luminescent, few are capable of white-light emission. Here, the authors incorporate a yellow-emitting guest molecule into the cavities of a blue-emitting metal–organic framework, and tune the composition to emit white light with relatively high quantum yield.

To compensate for the deficiencies of individual imaging modalities, lanthanide-based nanoparticles are ideal building blocks for multifunctional contrast agents. Herein, oleic acid-coated NaDyF4 nanorods (DyNPs) were synthesized by the hydrothermal method, and then coated with α-cyclodextrin (α-CD) and modified with gadolinium complex (Gd-DTPA) to obtain hydrophilic and functionalized nanoparticles (DyNPs-Gd). By loading the phosphorescent probe (iridium-complex) within the surface hydrophobic layer, the developed nanophosphors (DyNPs-Gd-Ir) could be further applied in phosphorescent cell labeling. The Dy in the host induces a high X-ray absorption ability for X-ray computed tomography (CT) and negative enhancement for T2-weighted magnetic resonance imaging (MRI), whereas positive contrast for T1-weighted MRI results from the Gd-DTPA. DyNPs-Gd-Ir has been successfully applied to T1- and T2-weighted MRI/CT in vivo. Toxicity studies demonstrated that DyNPs-Gd-Ir exhibited low toxicity to living systems. Therefore, DyNPs-Gd-Ir could be a platform for next-generation contrast agents for T1- and T2-weighted MRI/CT/phosphorescence multimodal imaging.

Correction for ‘Theoretical study and design of multifunctional phosphorescent platinum(ii) complexes containing triarylboron moieties for efficient OLED emitters’ by Yong Wu et al., Phys. Chem. Chem. Phys., 2015, DOI: 10.1039/c4cp04919e.