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Herein, we report the inaugural instance of N‐heterocyclic silylene (NHSi)‐coordinated copper amide emitters (2–5). These complexes exhibit thermally activated delayed fluorescence (TADF) and singlet‐triplet dual emission in anaerobic conditions. The NHSi‐Cu‐diphenylamide (2) complex demonstrates TADF with a very small ΔEST gap (0.01 eV), an absolute quantum yield of 11 %, a radiative rate of 2.55×105 s−1, and a short τTADF of 0.45 μs in the solid state. The dual emissive complexes (3–5) achieve an absolute quantum yield of up to 20 % in the solid state with a kISC rate of 1.82×108 s−1 and exhibit room temperature phosphorescence (RTP) with lifetimes up to 9 ms. The gradual decrease in the intensity of the triplet state of complex 3 under controlled oxygen exposure demonstrates its potential for future oxygen‐sensing applications. Complexes 2 and 3 have been further utilized to fabricate converted LEDs, paving the way for future OLED production using newly synthesized NHSi‐Cu‐amides. [ABSTRACT FROM AUTHOR]

Ratiometric fluorescent sensing based on dual-emitting fluorescent coordination polymers (FL-CPs) has attracted intense attention due to their sensing accuracy and easy visualization when compared with sensing relying solely on monochromatic FL-CPs. In this work, a series of rare-earth metal-based CPs, formuled as [(CH3)2NH2][Ln(bpdc)2] (Ln3+ = Y3+, Eu3+ and Tb3+, H2bpdc = biphenyl-4,4′-dicarboxylic acid), are presented, which show dual emission aroused from the Ln3+ ions and the inefficient intermolecular energy transfer from ligands to Ln3+ metals. For clarity, the as-made Ln-CPs are named Eu-bpdc, Tb-bpdc, and Y-bpdc based on the corresponding Ln3+. Notably, Eu-bpdc, presented as an example, could be used as FL sensing material ratiometric to Fe3+ ions. The ratio of FL intensity of Eu3+ ions to bpdc2− ligands (I415/I615) showed a good linear relationship with the concentrations of Fe3+ ions. Moreover, the detection process could be visibly monitored through a change from purple to blue when Eu-bpdc was used as an FL proble. This work provides a good example for exploring visibly ratiometric sensors based on FL-CPs. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) as a kind of sensing material plays an important role for environmental monitoring and human health. In this paper, we prepared a luminescent Cd‐MOF: [Cd2L·4H2O]·H2O. (H4L = 2,5‐bis‐(3,4‐dicarboxy‐phenyl)thiophene‐amide) under the solvothermal condition. Single crystal X‐ray diffraction analysis shows that Cd‐MOF has a 2D layer structure, and it exhibits a strong fluorescence emission at 470 nm. The sensing experiment displays Cd‐MOF as multitarget probe can selectively detect Cr (VI) anions and 4‐nitroaniline (4‐NA) with high sensitivity, good anti‐interference ability, and good recyclability. In addition, dual‐emission Eu3+@Cd‐MOF was obtained by encapsulating Eu3+ ions into Cd‐MOF, in which Cd‐MOF sensitizes Eu3+ ion emission. Accordingly, Eu3+@Cd‐MOF also acts as multitarget and self‐calibrated probe to selectively detect Cr (VI) ions and 4‐NA synchronously at the same conditions. However, the changes of fluorescence emissions of Eu3+@Cd‐MOF toward Cr (VI) ions are different from that of the original Cd‐MOF. The possible sensing mechanism be attributed to the competitive energy absorption between Cd‐MOF or Eu3+@Cd‐MOF and the analytes. All the results may provide broad prospects for developing multitarget sensing platform for sensing environment pollutants. [ABSTRACT FROM AUTHOR]

Efficient and stable scintillators play a crucial role in X‐ray detection applications. To enhance the luminescence efficiency under X‐ray excitation, the incorporation of multiple emission centers into scintillators is widely explored. Here, it is found that the cesium copper halide Cs5Cu3Cl6I2 exhibits dual emission centers, enabling high‐performance scintillators with an X‐ray light yield of 49000 photon MeV−1 and a low detection limit of 4 nGy s−1. The emissions of Cs5Cu3Cl6I2 are from intrinsic self‐trapped exciton (STE) and Frenkel defect‐assisted STE. High‐energy X‐rays can induce an increased fraction of Frenkel defect‐assisted STEs, which can serve as an effective scintillation channel. Furthermore, large‐area flexible scintillators with a high resolution of 18 lp mm−1 are developed, making them suitable for X‐ray imaging applications. These findings offer promising insights for developing more efficient scintillators. [ABSTRACT FROM AUTHOR]

Luminophores' dual emission (DE) properties hold great potential for realizing single‐component white organic light–emitting diodes (WOLEDs). This study illustrates that the unique and vibrant DE phenomena with different luminous mechanisms can be formed through simple modulation of molecular structures. Four target luminophores, namely 2‐TPE‐PPI, 2‐TPE‐PI, 2‐TPE‐An‐PPI, and 2‐TPE‐An‐PI, capable of DE under different conditions, are intentionally designed and successfully synthesized. Owing to the inherent flexibility of the minor molecular backbone and minor steric hindrance, 2‐TPE‐PPI and 2‐TPE‐PI exhibit DE spectra in dilute solutions with different solvent polarities. The intrinsic cause of the DE phenomenon in 2‐TPE‐An‐PPI and 2‐TPE‐An‐PI arises from the localized distribution of frontier molecular orbits resulting from the presence of an anthracene unit and the formation of an exciter group through intermolecular interactions involving anthracene. Remarkably, single‐emissive‐layer WOLEDs based on 2‐TPE‐An‐PPI and 2‐TPE‐An‐PI demonstrate stable white emission with CIE coordinates at (0.33, 0.39) and (0.30, 0.39), respectively, closely approaching the CIE coordinates of standard white light. Moreover, they maintain stable EL spectra from 4 to 10 V, an exceptional attribute rarely observed in many white light devices. [ABSTRACT FROM AUTHOR]

An assembly of metal nanoclusters driven by appropriate surface ligands and solvent environment may engender entirely new photoluminescence (PL). Herein, we first synthesize histidine (His) stabilized copper nanoparticles (CuNPs) and, subsequently, copper nanoclusters (CuNCs) from it using 3‐mercaptopropionic acid (MPA) as an etchant. The CuNCs originally emit bluish‐green (λem=470 nm) PL with a low quantum yield (QY∼1.8 %). However, it transformed into a dual‐emissive nanocluster assembly (Zn‐CuNCs) in the presence of Zn(II) salt, having a distinct blue emission band (λem=420 nm) and a red emission band (λem=615 nm) with eight times QY (∼9.1 %) enhancement. The temperature‐dependent emission spectra of Zn‐CuNCs depicted that the blue emission band persists for all the temperature ranges (0–80 °C) while the red emission band vanishes at high temperatures (70–80 °C). Thus, the blue emission may originate from the locally excited state (LES) emission of the nanoclusters, while the red emission originates from through‐space interaction (TSI) and Cu(I)...Cu(I) interaction within the assembly. Adding dimethyl sulfoxide (DMSO) further modifies the emission intensities; the red band was amplified four times, while the blue band was diminished by 2.5 times. The transmission electron microscopy (TEM) images unveiled that the Zn‐CuNCs are a large assembly of tiny nanoclusters, which become more compact in DMSO. The blue emission possesses steady‐state fluorescence anisotropy, while the red emission shows no anisotropy. Further, near‐perfect white light emission(WLE) was rendered with CIE coordinates of (0.33, 0.32) by combining the dual emission of the Zn‐CuNCs with the original green emission of the CuNCs. [ABSTRACT FROM AUTHOR]

Pillar[5]arene is a promising macrocyclic receptor of a chemical sensor showing shape-selective encapsulation of neutral molecules into the cavity, but the poor fluorescence properties remain a challenge. Herein, we report a pillar[5]arene coupled with 2-(2-hydroxyphenyl)benzoxazole (HBO), which displays bright fluorescence in both solution and the solid state. Owing to the excited-state intramolecular proton transfer (ESIPT) in the HBO moiety, greatly improved fluorescence is observed for the pillar[5]arene derivative in CHCl3 (Φ lum = 11%) and powder form (Φ lum = 25%). Moreover, the emission color changes from light green to blue when the powder sample is exposed to n -hexane vapor. The color change derives from variable dual emission via ESIPT and excimer-forming pathways, as suggested by fluorescence lifetime measurements at different wavelengths. Powder x-ray diffraction indicates that increased crystallinity and a small alteration in the solid-state structure leads to visible fluorescent chromism upon vapor encapsulation. [ABSTRACT FROM AUTHOR]

[Display omitted] Biological engineering bacteria hold great promise in tumor therapy due to their targeted delivery, tumor penetration, and tumor-specific activation capabilities. However, the use of live bacteria raises safety concerns, as they can potentially cause infections or adverse immune responses in patients. Additionally, most biological engineering bacteria are only responsive to blue light, which has limited penetration depth within biological tissues. To address these limitations, we have developed a nanoplatform that combines dual-emission upconversion nanoparticles (referred to as DDUCNPs), which can realize dual-wavelength emission under dual-wavelength excitation, with biological engineering bacteria for tumor treatment and the self-clearance of biological engineering bacteria after therapy in the near-infrared (NIR) window. This design allows us to utilize 980 nm light, which is converted to blue light by the DDUCNPs, to activate the bacteria and promote the controlled release of tumor necrosis factor-alpha (TNF-α) for precise tumor ablation. Subsequently, we employ 808 nm excitation to achieve light conversion into the red light, thereby activating photosensitizer molecules and generating singlet oxygen (ROS) for in vivo clearance of the bacteria involved in the treatment. Simultaneously, the generated ROS also undergoes photodynamic therapy (PDT) on the tumor to enhance the therapeutic effect. By combining these elements on a single platform, our system achieves the activation and self-clearance of biological engineering bacteria in the NIR window, effectively enabling tumor treatment. This approach overcomes the limitations of blue light penetration and addresses safety concerns associated with live bacteria, offering a promising strategy for precise and controlled tumor therapy. [ABSTRACT FROM AUTHOR]

Ag-In-Ga-S (AIGS) quantum dots (QDs) have recently attracted great interests due to the outstanding optical properties and eco-friendly components, which are considered as an alternative replacement for toxic Pb- and Cd-based QDs. However, enormous attention has been paid to how to narrow their broadband spectra, ignoring the application advantages of the broadband emission. In this work, the AIGS QDs with controllable broad green-red dual-emission are first reported, which is achieved through adjusting the size distribution of QDs by controlling the nucleation and growth of AIGS crystals. Resultantly, the AIGS QDs exhibit broad dual-emission at green- and red- band evidenced by photoluminescence (PL) spectra, and the PL relative intensity and peak position can be finely adjusted. Furthermore, the dual-emission is the intrinsic characteristics from the difference in confinement effect of large particles and tiny particles confirmed by temperature-dependent PL spectra. Accordingly, the AIGS QDs (the size consists of 17 nm and 3.7 nm) with 530 nm and 630 nm emission could successfully be synthesized at 220 °C. By combining the blue light-emitting diode (LED) chips and dual-emission AIGS QDs, the constructed white light-emitting devices (WLEDs) exhibit a continuous and broad spectrum like natural sunlight with the Commission Internationale de l’Eclairage (CIE) chromaticity coordinates of (0.33, 0.31), a correlated color temperature (CCT) of 5425 K, color rendering index (CRI) of 90, and luminous efficacy of radiation (LER) of 129 lm/W, which indicates that the AIGS QDs have huge potential for lighting applications.

Recently, an ever‐growing interest has been paid on organic single‐molecule white light‐emitting materials for effective white organic light‐emitting diodes (WOLEDs). However, subject to Kasha's rule, photons can only be emitted from the lowest excited state and thus panchromatic or dual emissions are extremely forbidden, which results in a certain challenge in achieving white emission. Herein, a strategy of synergetic carbonyl and heptagonal structure is proposed for organic single‐molecule white light emission and demonstrated by TAO/TABO/TA2O organic luminescent materials that are modified on aryl ketones/amine fragments. Among them, due to the robust intermolecular interactions triggered by synergetic carbonyl and heptagonal structure, TA2O exhibits vibrant monomer and dimer photoluminescence with dual thermally activated delayed fluorescence (TADF) characteristics. As a result, the first single‐molecule dual‐TADF WOLED based on the synergetic system is successfully fabricated with an external quantum efficiency of 7.2%. This study not only expands the scope of carbonyl and heptagonal structure for novel optoelectronic properties and applications but also opens new avenues for the development of efficient single‐molecule WOLEDs with dual TADF mechanisms. [ABSTRACT FROM AUTHOR]

2,4-dimethyl-6-(1-phenyl-1H-benzimidazol-2-yl)phenol (DPBP) has been prepared and characterized by 1H NMR, 13C NMR, mass spectral studies and elemental analysis. DPBP shows On/off fluorescence system (fluorescence enhancing and quenching) by tuning with Fe3+ metal ion and H3PO4. Addition of Fe3+ ions into DPBP results in quenching of fluorescence. Other cations, including Zn2+, Ni2+, Pb2+, Ca2+, Co2+, Cd2+ and Mg2+ had little effect in the fluorescence intensity. The addition of H3PO4 with Fe3+-DPBP complex results in the enhanced fluorescence due to the detachment of Fe3+-DPBP complex. Dual emission has been observed by DPBP in non-polar solvent medium whereas single emission was observed in polar solvents due to Intra and Intermolecular hydrogen bonding respectively. Shorter wavelength emission of DPBP is due to enol rotamer and longer wavelength emission of DPBP is due to keto rotamer. [ABSTRACT FROM AUTHOR]

Fluorescent probes incorporating the excited-state intramolecular proton transfer (ESIPT) phenomenon have emerged as versatile tools in scientific research. These probes exhibit dual emission, resulting from the unique transfer of a proton within the molecule upon excitation. This property makes ESIPT-based Schiff bases highly attractive for metal detection, cell imaging, and sensing biologically important molecules. In metal detection, the spectral changes of ESIPT-based Schiff bases upon interaction with metal ions enable the development of sensitive and selective sensors. For cell imaging, their photophysical properties make them ideal for labeling cellular components and facilitating multicolor imaging. In sensing biomolecules, ESIPT-based Schiff bases offer selective detection of interactions and enzymatic activities. Integration of these probes holds great promise for applications in environmental monitoring, biomedical research, and healthcare. This review focuses on the photoluminescent properties and application of ESIPT dual emission Schiff bases for sensing of metal ions, biologically relevant molecules and cell imaging. [ABSTRACT FROM AUTHOR]

The dual emission (DE) characteristics of atomically precise copper nanoclusters (Cu NCs) are of significant theoretical and practical interest. Despite this, the underlying mechanism driving DE in Cu NCs remains elusive, primarily due to the complexities of excited state processes. Herein, a novel [Cu4(PPh3)4(C≡C−p−NH2C6H4)3]PF6 (Cu4) NC, shielded by alkynyl and exhibiting DE, was synthesized. Hydrostatic pressure was applied to Cu4, for the first time, to investigate the mechanism of DE. With increasing pressure, the higher‐energy emission peak of Cu4 gradually disappeared, leaving the lower‐energy emission peak as the dominant emission. Additionally, the Cu4 crystal exhibited notable piezochromism transitioning from cyan to orange. Angle‐dispersive synchrotron X‐ray diffraction results revealed that the reduced inter‐cluster distances under pressure brought the peripheral ligands closer, leading to the formation of new C−H⋅⋅⋅N and N−H⋅⋅⋅N hydrogen bonds in Cu4. It is proposed that these strengthened hydrogen bond interactions limit the ligands′ vibration, resulting in the vanishing of the higher‐energy peak. In situ high‐pressure Raman and vibrationally resolved emission spectra demonstrated that the benzene ring C=C stretching vibration is the structural source of the DE in Cu4. [ABSTRACT FROM AUTHOR]

Luminescent Mn(II)‐based organic–inorganic hybrid halides have drawn attention as potential materials for sensing and photonics applications. Here, the synthesis and characterization of methylammonium (MA) manganese bromide ((MA)nBrxMn(H2O)2, (n = 1, 4 and x = 3, 6)) with different stoichiometries of the organic cation and inorganic counterpart, are reported. While the Mn2+ centers have an octahedral conformation, the two coordinating water molecules are found either in cis (1) or in trans (2) positions. The photophysical behavior of 1 reflects the luminescence of Mn2+ in an octahedral environment. Although Mn2+ in 2 also has octahedral coordination, at room temperature dual emission bands at ≈530 and ≈660 nm are observed, explained in terms of emission from Mn2+ in tetragonally compressed octahedra and self‐trapped excitons (STEs), respectively. Above the room temperature, 2 shows quasi‐tetrahedral behavior with intense green emission, while at temperatures below 140 K, another STE band emerges at 570 nm. Time‐resolved experiments (77–360 K) provide a clear picture of the excited dynamics. 2 shows rising components due to STEs formation equilibrated at room temperature with their precursors. Finally, the potential of these materials for the fabrication of color‐tunable down‐converted light‐emitting diode (LED) and for detecting polar solvent vapors is shown. [ABSTRACT FROM AUTHOR]

DNA‐stabilized silver nanoclusters (DNA‐AgNCs) are a class of emitters that have primarily been studied for their molecular‐like photophysical properties with ns‐lived fluorescence. However, µs‐lived luminescence has recently been reported for an increasing number of DNA‐AgNCs, but little is still known about the origin of the long‐lived emission. To deepen the understanding of the long‐lived state, (DNA)2‐[Ag11]7+, an emitter with short‐ and long‐lived dual emission, is studied. By examining crystals of (DNA)2‐[Ag11]7+, it is found that the fluorescence and luminescence transitions are orthogonal to each other, which implies that components orthogonal to the long axis of the AgNC, such as the nucleobases, contribute significantly to the polarization character of the long‐lived luminescent state. The effect of the hydration level on the dual emission of dried (DNA)2‐[Ag11]7+ droplets is also investigated, and it is found that water drastically reduces emission from the long‐lived state and causes a redshift of the emission. Finally, an unusual excitation intensity‐dependent response of dried (DNA)2‐[Ag11]7+ droplets is noticed. This is ascribed to the heterogeneous local environment of the amorphous solid resulting in different conformations of (DNA)2‐[Ag11]7+ with different optically activated delayed fluorescence probabilities. The presented results provide new key insights into the nature of the long‐lived state of DNA‐AgNCs. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal complexes of copper subgroup metals are actively studied objects for temperature sensors. Their luminescence arising from the 3ILCT, 3MLCT or 3CC excited states is characterized by emission in all ranges of visible spectra and high quantum yields. Due to the ability of the complexes to emit in a dual band mode, these complexes are attractive for the temperature sensing in the ratiometric mode. Dual emission of complexes is usually susceptible of the irregular changes in intensity of two emission bands during the temperature changes. This is an important and necessary property for the utilization of phosphors as ratiometric thermometers. The structures and emission properties of gold(i) and copper(i) complexes are considered with the aim to demonstrate the possibility to apply such complexes as ratiometric molecular luminescent thermometers for the remote control of the object's temperature. [ABSTRACT FROM AUTHOR]

The relativistic effect enhances spin‐orbit coupling (SOC), making metal complexes potential candidates for phosphorescent OLED emitters. However, the relativistic effect profoundly influences the donor and acceptor interactions (D‐A), resulting in unique electron transition processes. By stabilizing the s orbitals and destabilizing the d orbitals of the center metal atom, the relativistic effect enhances donation, back donation, and the trans effect in PtN1N more than in PdN1N. Particularly, the back donation in PtN1N is approximately four times greater than that in PdN1N, contributing to the greater stability and rigidity in PtN1N. Furthermore, the relativistic effect enhances the SOC and reduces the excitation energy and stabilizes the excited states of PtN1N. Consequently, the radiative decay rate kp$$ {\mathrm{k}}_{\mathrm{p}} $$ and non‐radiative rate knr$$ {\mathrm{k}}_{\mathrm{nr}} $$ are accelerated simultaneously. The reverse intersystem crossing rate kRISCT3→S1$$ {\mathrm{k}}_{\mathrm{RISC}}\left({\mathrm{T}}_3\to {\mathrm{S}}_1\right) $$ in PdN1N is accelerated by high temperature, which is responsible for thermally activated delayed fluorescence (TADF). [ABSTRACT FROM AUTHOR]

Rhodamine-B grafted carbon dots (RhB-CDs) with double emission fluorescence are developed, one of which has excitation dependence, while the other have not. The prepared RhB-CDs have good dispersibility, uniform spherical shape, and excellent water solubility. They could be used to specifically detect Fe3+ ions in an aqueous solution with the detection limit of 1.1 x 10-6 m and with good anti-interference ability, because Fe3+ ions are easier to combine with hydroxyl groups on the surface of RhB-CDs to form aggregates (such as ferric hydroxide) than other metal ions, which lead to the fluorescence quenching of RhB-CDs. Fe3+ ions not only quench the fluorescence intensity of both double emission peaks of RhB-CDs, but also change the relative fluorescence intensity of these two fluorescence emission peaks. Therefore, two different fluorescence analysis methods are used to specifically identify iron ions and the results are consistent with each other. At the same time, the double emission fluorescent RhB-CDs have low hemolysis rate and cytotoxicity, indicating that RhB-CDs do little harm to cells and are further used to detect Fe3+ ions in cells through fluorescence bioimaging. All of the above indicates that the prepared RhB-CDs would have potential application value in detecting iron ions in blood and cells. [ABSTRACT FROM AUTHOR]

The short wavelength (SW) emission region of the materials employing strong donor (DS) phenothiazine (PTZ) is generally correlated to its quasi‐axial (QAPTZ) conformer arrangement. This propels to investigate the specific role of weak donors (DW) such as carbazole (CZ) in determining the emission characteristics of molecular heredity (MH) type structural design encompassing dual donors of varying strength. For this purpose, a common DS(PTZ)–Acceptor unit is linked to the DW(CZ) unit via different linkage positions to form M1, M2, and M3, which not only alters the absorption and dual emission characteristics but also influences the delayed fluorescence phenomenon. The SW emission originates by minimizing the aggregation factor rather than by literature envisaged QAPTZ conformer. Incorporating M1 as a single molecular white light emitter (SMWLE) in near UV light emitting diode (LED) devices results in cold white light emission with CRI of 68 and CIE of (0.24, 0.33), while its corresponding solution‐processed organic light‐emitting diode devices delivers warm white electroluminescence with an EQE of 5.8%. Overall, this work demonstrates the significant contribution of the DW in attaining the white light emission characteristics of MH molecular design not only at the molecular level but also in practical light‐emitting devices. [ABSTRACT FROM AUTHOR]

Organic room temperature phosphorescent (ORTP) materials with stimuli-responsive, multicomponent emissive behaviour are extremely desirable for various applications. The derivative of cyclic triimidazole (TT) functionalized with an ethynyl group, TT-CCH, is isolated and investigated. The compound possesses crystallization-enhanced emission (CEE) comprising dual fluorescence and dual phosphorescence of both molecular and supramolecular origin with aggregation-induced components highly sensitive to grinding. The mechanisms involved in the emissions have been disclosed thanks to combined structural, spectroscopic and computational investigations. In particular, strong CH⋯N hydrogen bonds are deemed responsible, for the first time in the TT family, together with frequently observed π⋯π stacking interactions, for the aggregated fluorescence and phosphorescence. [ABSTRACT FROM AUTHOR]

Helical nanographenes have garnered substantial attention owing to their finely adjustable optical and semiconducting properties. The strategic integration of both helicity and heteroatoms into the nanographene structure, facilitated by a boron‐oxygen‐based multiple resonance (MR) thermally activated delayed fluorescence (TADF), elevates its photophysical and chiroptical features. This signifies the introduction of an elegant category of helical nanographene that combines optical (TADF) and chiroptical (CPL) features. In this direction, we report the synthesis, optical, and chiroptical properties of boron, oxygen‐doped Π‐extended helical nanographene. The π‐extension induces distortion in the DOBNA‐incorporated nanographene, endowing a pair of helicenes, (P)‐B2NG, and (M)‐B2NG exhibiting circularly polarized luminescence with glum of −2.3×10−3 and +2.5×10−3, respectively. B2NG exhibited MR‐TADF with a lifetime below 5 μs, and a reasonably high fluorescence quantum yield (50 %). Our molecular design enriches the optical and chiroptical properties of nanographenes and opens up new opportunities in multidisciplinary fields. [ABSTRACT FROM AUTHOR]

Abstract Luminescent Mn(II)‐based organic–inorganic hybrid halides have drawn attention as potential materials for sensing and photonics applications. Here, the synthesis and characterization of methylammonium (MA) manganese bromide ((MA)nBrxMn(H2O)2, (n = 1, 4 and x = 3, 6)) with different stoichiometries of the organic cation and inorganic counterpart, are reported. While the Mn2+ centers have an octahedral conformation, the two coordinating water molecules are found either in cis (1) or in trans (2) positions. The photophysical behavior of 1 reflects the luminescence of Mn2+ in an octahedral environment. Although Mn2+ in 2 also has octahedral coordination, at room temperature dual emission bands at ≈530 and ≈660 nm are observed, explained in terms of emission from Mn2+ in tetragonally compressed octahedra and self‐trapped excitons (STEs), respectively. Above the room temperature, 2 shows quasi‐tetrahedral behavior with intense green emission, while at temperatures below 140 K, another STE band emerges at 570 nm. Time‐resolved experiments (77–360 K) provide a clear picture of the excited dynamics. 2 shows rising components due to STEs formation equilibrated at room temperature with their precursors. Finally, the potential of these materials for the fabrication of color‐tunable down‐converted light‐emitting diode (LED) and for detecting polar solvent vapors is shown.

Ratiometric fluorescent sensing based on dual-emitting fluorescent coordination polymers (FL-CPs) has attracted intense attention due to their sensing accuracy and easy visualization when compared with sensing relying solely on monochromatic FL-CPs. In this work, a series of rare-earth metal-based CPs, formuled as [(CH3)2NH2][Ln(bpdc)2] (Ln3+ = Y3+, Eu3+ and Tb3+, H2bpdc = biphenyl-4,4′-dicarboxylic acid), are presented, which show dual emission aroused from the Ln3+ ions and the inefficient intermolecular energy transfer from ligands to Ln3+ metals. For clarity, the as-made Ln-CPs are named Eu-bpdc, Tb-bpdc, and Y-bpdc based on the corresponding Ln3+. Notably, Eu-bpdc, presented as an example, could be used as FL sensing material ratiometric to Fe3+ ions. The ratio of FL intensity of Eu3+ ions to bpdc2− ligands (I415/I615) showed a good linear relationship with the concentrations of Fe3+ ions. Moreover, the detection process could be visibly monitored through a change from purple to blue when Eu-bpdc was used as an FL proble. This work provides a good example for exploring visibly ratiometric sensors based on FL-CPs.

Fluorescent base analogues (FBAs) have become useful tools for applications in biophysical chemistry, chemical biology, live‐cell imaging, and RNA therapeutics. Herein, two synthetic routes towards a novel FBA of uracil named qU (quadracyclic uracil/uridine) are described. The qU nucleobase bears a tetracyclic fused ring system and is designed to allow for specific Watson‐Crick base pairing with adenine. We find that qU absorbs light in the visible region of the spectrum and emits brightly with a quantum yield of 27 % and a dual‐band character in a wide pH range. With evidence, among other things, from fluorescence lifetime measurements we suggest that this dual emission feature results from an excited‐state proton transfer (ESPT) process. Furthermore, we find that both absorption and emission of qU are highly sensitive to pH. The high brightness in combination with excitation in the visible and pH responsiveness makes qU an interesting native‐like nucleic acid label in spectroscopy and microscopy applications in, for example, the field of mRNA and antisense oligonucleotide (ASO) therapeutics. [ABSTRACT FROM AUTHOR]

The accurate thermosensing requires a minimum impact of autofluorescence and light scattering from the samples. In this study, we discovered that commercially available benzene‐1,4‐diboronic acid (BDBA) doped co‐crystals with trimethylolpropane (TMP) exhibit excellent thermochromic dual phosphorescence properties over a wide temperature range from −132 to 40 °C, despite its simple structure that does not have any donor‐acceptor linkage. The dual phosphorescence was consisted of monomeric benzene‐1,4‐diboronate (BDBA ester) and aggregation‐stabilized species. With an increase in temperature, the emission intensity from the monomeric state significantly decreased, whereas that originating from the aggregated state remained almost constant owing to the difference in their thermal stabilities. Further investigation revealed that molecular distortions in singlet excited states enable efficient intersystem crossing, causing efficient phosphorescence from the monomeric state of BDBA ester. [ABSTRACT FROM AUTHOR]

The dual emission (DE) feature in materials holds great potential to revolutionize the development of one‐component system white organic light‐emitting diodes (WOLEDs). However, the reported DE materials remain scarce owing to the formidable challenge of breaking Kasha's rule and managing the intricate energy/charge transfer processes. Herein, we have introduced a groundbreaking DE AIEgen, 2CzAn‐TPE, which possesses a simple structure and undergoes Z‐to‐E isomerization and exhibits yellow and red fluorescence powders for pre‐ and post‐sublimation, respectively. With relatively lower potential energy, Z‐conformation ((Z)‐1,2‐diphenyl‐1,2‐bis(4‐(10‐(9‐phenyl‐9H‐carbazol‐3‐yl)anthracen‐9‐yl)phenyl)ethene) of 2CzAn‐TPE can be readily transformed into E‐conformation ((E)‐1,2‐diphenyl‐1,2‐bis(4‐(10‐(9‐phenyl‐9H‐carbazol‐3‐yl)anthracen‐9‐yl)phenyl)ethene) via vacuum sublimation. The utilization of X‐ray diffraction and grazing‐incidence‐wide‐angle X‐ray scattering techniques confirms the structural transformation, while the crystallographic analysis reveals the establishment of numerous intermolecular CH···π interactions between the tetraphenylethene (TPE) moiety and both the anthracene and carbazole units. This allows a densely packed molecular arrangement, thereby offering propitious conditions for excimer generation in the E‐conformation aggregated state. By utilizing the sublimated 2CzAn‐TPE as an emitter, a nondoped one‐component WOLED was prepared, exhibiting an exceptionally high external quantum efficiency (EQE) of 5.0%, which represents one of the highest performances among all one‐component WOLEDs. This research introduces a novel, simple, and efficient approach to realize highly efficient one‐molecule WOLEDs. [ABSTRACT FROM AUTHOR]

The two enantiomers of chiral phosphonate 4-phenyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine 4-oxide, O=PPh(BINOL), were synthesized from the proper 1,1′-bi-2-naphtol (BINOL) enantiomer and characterized. The structure of the (S)-enantiomer was elucidated by means of single-crystal X-ray diffraction. The reaction with anhydrous ZnBr2 afforded complexes having the general formula [ZnBr2{O=PPh(BINOL)}2] that showed intense fluorescence centered in the near-UV region rationalized on the basis of TD-DFT calculations. The corresponding Mn(II) complexes with the general formula [MnX2{O=PPh(BINOL)}2] (X = Cl, Br) exhibited dual emission upon excitation with UV light, with the relative intensity of the bands dependent upon the choice of the halide. The highest energy transition is comparable with that of the Zn(II) complex, while the lowest energy emission falls in the red region of the spectrum and is characterized by lifetimes in the hundreds of microseconds range. Although the emission at lower energy can also be achieved by direct excitation of the metal center, the luminescence decay curves suggest that the band in the red range is possibly derived from BINOL-centered excited states populated by intersystem crossing. [ABSTRACT FROM AUTHOR]

The advantages of utilizing dual emission display in relation to information interaction and customized display have been widely acknowledged. Organic light‐emitting devices (OLEDs) are an effective solution for future dual emission displays, however, the influence of electrode materials and device structure results in significant differences in the optical performance on both sides. Here, we adjust the optical microcavity effect to balance the light output from both sides so that the top and bottom of the display can be seen with the same brightness and chromaticity. The structure of an OLED for dual emission display has been fabricated. [ABSTRACT FROM AUTHOR]

Abstract The dual emission (DE) feature in materials holds great potential to revolutionize the development of one‐component system white organic light‐emitting diodes (WOLEDs). However, the reported DE materials remain scarce owing to the formidable challenge of breaking Kasha's rule and managing the intricate energy/charge transfer processes. Herein, we have introduced a groundbreaking DE AIEgen, 2CzAn‐TPE, which possesses a simple structure and undergoes Z‐to‐E isomerization and exhibits yellow and red fluorescence powders for pre‐ and post‐sublimation, respectively. With relatively lower potential energy, Z‐conformation ((Z)‐1,2‐diphenyl‐1,2‐bis(4‐(10‐(9‐phenyl‐9H‐carbazol‐3‐yl)anthracen‐9‐yl)phenyl)ethene) of 2CzAn‐TPE can be readily transformed into E‐conformation ((E)‐1,2‐diphenyl‐1,2‐bis(4‐(10‐(9‐phenyl‐9H‐carbazol‐3‐yl)anthracen‐9‐yl)phenyl)ethene) via vacuum sublimation. The utilization of X‐ray diffraction and grazing‐incidence‐wide‐angle X‐ray scattering techniques confirms the structural transformation, while the crystallographic analysis reveals the establishment of numerous intermolecular CH···π interactions between the tetraphenylethene (TPE) moiety and both the anthracene and carbazole units. This allows a densely packed molecular arrangement, thereby offering propitious conditions for excimer generation in the E‐conformation aggregated state. By utilizing the sublimated 2CzAn‐TPE as an emitter, a nondoped one‐component WOLED was prepared, exhibiting an exceptionally high external quantum efficiency (EQE) of 5.0%, which represents one of the highest performances among all one‐component WOLEDs. This research introduces a novel, simple, and efficient approach to realize highly efficient one‐molecule WOLEDs.

Herein, we report the synthesis of two "partially embedded fused‐dihydropyridazine N‐aryl aza[5]helicene derivatives" (PDHs) and the demonstration of their intrinsic photo‐triggered multi‐functional properties based on a Kekulé biradical structure. Introducing bulky electron‐withdrawing trifluoromethyl or pentafluoroethyl groups into the aza[5]helicene framework (PDH‐CF3 and −C2F5) gives PDH axial chirality based on the helicity of the P and M forms, even at room temperature. Upon photo‐irradiation of PDH‐CF3 in a frozen solution, an ESR signal from the triplet biradical with zero‐field splitting values, generated by N−N bond dissociation, was observed. However, when the irradiation was turned off, the ESR signal became silent, thus indicating the existence of two equilibria: between the biradical and quinoidal forms based on the Kekulé structure, and between N−N bond cleavage and recombination. The observed photo‐ and thermally induced behaviors indicate that T‐type photochromic molecules are involved in the photoisomerization mechanism involving the two equilibria. Inspired by the photoisomerization, chirality control of PDH by photoracemization was achieved. Multiple functionalities, such as T‐type photochromism, photo‐excitation‐mediated triplet biradical formation, and photoracemization, which are attributed to the "partially embedded dihydropyridazine" structure, are demonstrated. [ABSTRACT FROM AUTHOR]

Three monoruthenium complexes 1(PF6)2–3(PF6)2 bearing an N(CH3)-bridged ligand have been synthesized and characterized. These complexes have a general formula of [Ru(bpy)2(L)](PF6)2, where L is a 2,5-di(N-methyl-N'-(pyrid-2-yl)amino)pyrazine (dapz) derivative with various substituents, and bpy is 2,2′-bipyridine. The photophysical and electrochemical properties of these compounds have been examined. The solid-state structure of complex 3(PF6)2 is studied by single-crystal X-ray analysis. These complexes show two well-separated emission bands centered at 451 and 646 nm (Δλmax = 195 nm) for 1(PF6)2, 465 and 627 nm (Δλmax = 162 nm) for 2(PF6)2, and 455 and 608 nm (Δλmax = 153 nm) for 3(PF6)2 in dilute acetonitrile solution, respectively. The emission maxima of the higher-energy emission bands of these complexes are similar, while the lower-energy emission bands are dependent on the electronic nature of substituents. These complexes display two consecutive redox couples owing to the stepwise oxidation of the N(CH3)-bridged ligand and ruthenium component. Moreover, these experimental observations are analyzed by computational investigation. [ABSTRACT FROM AUTHOR]

Organic room temperature phosphorescent (ORTP) materials with stimuli-responsive, multicomponent emissive behaviour are extremely desirable for various applications. The derivative of cyclic triimidazole (TT) functionalized with an ethynyl group, TT-CCH, is isolated and investigated. The compound possesses crystallization-enhanced emission (CEE) comprising dual fluorescence and dual phosphorescence of both molecular and supramolecular origin with aggregation-induced components highly sensitive to grinding. The mechanisms involved in the emissions have been disclosed thanks to combined structural, spectroscopic and computational investigations. In particular, strong CH⋯N hydrogen bonds are deemed responsible, for the first time in the TT family, together with frequently observed π⋯π stacking interactions, for the aggregated fluorescence and phosphorescence.

Eco-friendly, biomass derived single component luminescent materials with dual emission bands hold immense potential in white light emitting devices (WLED). Compared to WLED fabricated from different color emitting carbon nanoparticles, self-reabsorption and degradation will be negligible in single system white light emitting materials which guarantees stability in long run. Herein, we report a facile, inexpensive and sustainable direct thermal decomposition method to synthesize carbon nanoparticles with dual emission bands. Addition of PVP could efficiently enhance the red emission band of carbon nanoparticles. The excitation dependent broad blue-green emission and excitation independent narrow red emission helps to obtain white light emitting carbon nanoparticles. Upon change in excitation wavelength from 410 nm to 370 nm, white light emissions are obtained with tunable CCT value from 2648 K to 8980 K respectively. By virtue of this tunable warm to cool white light emission, single system WLED can be designed suitable for both indoor and outdoor applications.

Dual-emissive fluorescent carbon dots (CDs) were prepared through the solvothermal method with citric acid and urea as raw materials and dimethylformamide as the solvent. Two emission peaks were observed at 465 nm and 630 nm. Hg2+ could selectively quench the fluorescence at 630 nm, but the fluorescence intensity at 465 nm was less affected. Accordingly, a ratiometric fluorescence sensor for Hg2+ detection was developed, with a linear detection range of 0.5–40 μM and a limit of detection (LOD) of 37 nM. The dual-emissive CDs were loaded on the surface of the filter paper to fabricate Hg2+ detection test paper. The color of the test paper could be changed from pink purple to blue by the addition of Hg2+, and thus the qualitative and quantitative detection of Hg2+ could be realized. The concentration distinguishable by the naked eye reached 50 μM, and the quantitative detection range was 5–10,000 μM. This method shows excellent selectivity for Hg2+ and can be used to detect Hg2+ in real water samples, providing a highly potential sensing platform for rapid on-site detection of mercury ions. [ABSTRACT FROM AUTHOR]

Polychlorinated (hetero)arenes have shown great promise for organic optoelectronics applications. However, the harsh synthetic routes for polychlorinated compounds and the possible luminescence quenching from the compact intermolecular π–π stacking induced by chlorine atoms limit their investigations and applications in luminescent materials. Herein, two isomeric polychlorinated polycyclic aromatic hydrocarbon (PAH) compounds JY‐1‐Cl and JY‐2‐Cl consisting of rigidified aryl ketones and amine are designed and synthesized under mild conditions through nucleophilic chlorination intermediated by an electron donor‐acceptor complex. Among them, as a result of the strong π–π interactions induced by chlorine atoms, JY‐2‐Cl exhibits bright monomer and dimer emissions with dual thermally activated delayed fluorescence (TADF) characters. Notably, compared with the non‐chlorinated compounds, a high photoluminescence quantum yield is maintained after introducing multiple chlorine atoms into JY‐2‐Cl. The first dual‐TADF organic light‐emitting diodes are also successfully fabricated with maximum external quantum efficiency as high as 29.1 % by employing JY‐2‐Cl as emitter. This work presents a new paradigm and synthesis of polychlorinated amine‐carbonyl PAHs and demonstrates the great potential of the chlorinated materials for luminescent applications. [ABSTRACT FROM AUTHOR]

A series of new platinum square planar complexes [Pt(NCN)L]+/0 with the pincer N^C^N cyclometallated ligand (NC(H)N = 1,3-bis(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)benzene) containing the following L: Cl−, acetonitrile, pyridine, dimethylaminopyridine, 2,6-dimethylphenylisocyanide, has been synthesized. Application of bridging acetate ion as L ligand allowed obtaining a binuclear [Pt(NCN)]2OOCCH3 complex. The bulky and rigid structure of N^C^N-ligand provokes instability of its pincer coordination that makes possible transformation of the molecular architecture to give a heteronuclear complex with the Pt-Ag-Pt coordination core. The composition and structure of the obtained compounds were characterized in solution and in the solid state using ESI mass-spectrometry, NMR spectroscopy, elemental analysis, and single-crystal XRD crystallography. The complexes luminesce in solid state, solution, and in polymeric matrix demonstrating moderate to bright emission at ca. 550 nm with quantum yields up to 22% and lifetime of excited state up to 22 µs. TD DFT computational approach together with analysis of the photophysical properties in different media reveals the predominant ligand-centered 3IL nature of the radiative excited state localized at the N^C^N-ligand. The ancillary ligand L demonstrates a minor influence on the energy of emission but affects dramatically emission efficiency and lifetime. The chloride complex displays dual (fluorescence and phosphorescent) luminescence due to labile coordination of an N-coordinated functionality that produces a dangling aromatic fragment, which gives emission from a singlet excited state. [ABSTRACT FROM AUTHOR]

The two enantiomers of chiral phosphonate 4-phenyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine 4-oxide, O=PPh(BINOL), were synthesized from the proper 1,1′-bi-2-naphtol (BINOL) enantiomer and characterized. The structure of the (S)-enantiomer was elucidated by means of single-crystal X-ray diffraction. The reaction with anhydrous ZnBr2 afforded complexes having the general formula [ZnBr2{O=PPh(BINOL)}2] that showed intense fluorescence centered in the near-UV region rationalized on the basis of TD-DFT calculations. The corresponding Mn(II) complexes with the general formula [MnX2{O=PPh(BINOL)}2] (X = Cl, Br) exhibited dual emission upon excitation with UV light, with the relative intensity of the bands dependent upon the choice of the halide. The highest energy transition is comparable with that of the Zn(II) complex, while the lowest energy emission falls in the red region of the spectrum and is characterized by lifetimes in the hundreds of microseconds range. Although the emission at lower energy can also be achieved by direct excitation of the metal center, the luminescence decay curves suggest that the band in the red range is possibly derived from BINOL-centered excited states populated by intersystem crossing.

Three donor‐acceptor compounds based on the imidazo‐pyrazine‐5,6‐dicarbonitrile (IPDC) acceptor were synthesized. The IPDC emitters exhibit blue to near‐infrared (NIR) emission with up to 54 % photoluminescent quantum yield. 9,9‐Dimethyl‐9,10‐dihydroacridine (ACR), phenoxazine (POX), and phenothiazine (PTZ) served as electron donors. IPDC‐POX displayed NIR emission in toluene solution, while showing room‐temperature phosphorescence in the solid state. IPDC‐ACR exhibited yellow thermally activated delayed fluorescence. Interestingly, dual‐emissive behavior as well as excitation‐dependent thermally activated delayed fluorescence (TADF) was found for IPDC‐PTZ, arising from the two conformers of phenothiazine derivatives. Overall, this work describes a novel strong electron acceptor from the fusion of imidazole, pyrazine, and nitrile functional groups into one conjugated heterocycle for materials exhibiting NIR emission, TADF, and/or room‐temperature phosphorescence (RTP). [ABSTRACT FROM AUTHOR]

Today we see an increasing demand for new fluorescent materials exhibiting various sensory abilities due to their broad applicability ranging from the construction of flexible devices to bioimaging. In this paper, we report on the new fluorescent pigments AntTCNE, PyrTCNE, and PerTCNE which consist of 3–5 fused aromatic rings substituted with tricyanoethylene fragments forming D-π-A diad. Our studies reveal that all three compounds exhibit pronounced rigidochromic properties, i.e., strong sensitivity of their fluorescence to the viscosity of the local environment. We also demonstrate that our new pigments belong to a very rare type of organic fluorophores which do not obey the well-known empirical Kasha'rule stating that photoluminescence transition always occurs from the lowest excited state of an emitting molecule. This rare spectral feature of our pigments is accompanied by an even rarer capability of spectrally and temporally well-resolved anti-Kasha dual emission (DE) from both higher and lowest electronic states in non-polar solvents. We show that among three new pigments, PerTCNE has significant potential as the medium-bandgap non-fullerene electron acceptor. Such materials are now highly demanded for indoor low-power electronics and portable devices for the Internet-of-Things. Additionally, we demonstrate that PyrTCNE has been successfully used as a structural unit in template assembling of the new cyanoarylporphyrazine framework with 4 D-π-A dyads framing this macrocycle (Pyr4CN4Pz). Similarly to its structural unit, Pyr4CN4Pz is also the anti-Kasha fluorophore, exhibiting intensive DE in viscous non-polar medium and polymer films, which strongly depends on the polarity of the local environment. Moreover, our studies showed high photodynamic activity of this new tetrapyrrole macrocycle which is combined with its unique sensory capacities (strong sensitivity of its fluorescent properties to the local environmental stimuli such as viscosity and polarity. Thus, Pyr4CN4Pz can be considered the first unique photosensitizer that potentially enables the real-time combination of photodynamic therapy and double-sensory approaches which is very important for modern biomedicine. [ABSTRACT FROM AUTHOR]

A conformationally restricted P,N‐ligand capable of the design of polynuclear copper(I) complexes was synthesized via the reaction of primary pyridylphosphine, paraformaldehyde, and benzhydrylamine. The reaction of the ligand with copper(I) iodide leads to the tetranuclear copper(I) complex with the octahedral type of copper‐iodide core. Different orientation of coordination bonds of the ligands relative to the P,N2‐heterocyclic fragments and to the Cu4I4 cores leads to the existence of two types of conformers of the complex with "compact" or "stretched" geometry of the Cu4I4 cluster. This lability of the complex allowed for obtaining two crystalline phases displaying green or red luminescence. The TDDFT computations along with XRD structural analysis gave a strong interpretation of the green emission belonging to the "compact" form of the complex and belonging of the red emission to the "stretched" form. Moreover, both crystalline phases demonstrate the strong vapochromic responses of luminescence on the vapors of wide range of solvents. [ABSTRACT FROM AUTHOR]

[Display omitted] • A ratiometric fluorescent probe exhibit specific response to NO 2 – using N-CDs. • The detection of NO 2 – is achieved through IFE and FRET. • The low detection limit and quantification for NO 2 – are 52 nM and 173 nM. • A N-CDs/LFASs is integrated with N-CDs, lateral flow assay strips and smartphone. • The N-CDs/LFASs possesses excellent linearity range, selectivity and sensitivity. Nitrite ion (NO 2 –), renowned for its potent antiseptic properties and color-preserving abilities, potentially leads to carcinogenesis and hypertension if consumed excessively. Herein, a ratiometric fluorescent probe exhibits specific response to NO 2 – using nitrogen-doped carbon dots (N-CDs) with a low detection limit (LOD) as low as 52 nM and a low quantification limit (LOQ) of 173 nM. Initially, the emission peaks at 495 nm and 415 nm decrease as result of the internal filtration effect (IFE). With further increasing NO 2 – concentration, the reaction between NO 2 – and N-CDs forms an azoic compound (N-CDs@NO 2 –), which promotes the instant quenching of the emission peak at 415 nm through fluorescence resonance energy transfer (FRET). Moreover, portable N-CDs/LFASs devices with smartphone are successfully applied to visually identify NO 2 – with the exceptional LOD, achieving excellent recoveries and high precision in real sample. Therefore, this newly N-CDs/LFASs offers a reliable means for the NO 2 – detection, showcasing potential applications. [ABSTRACT FROM AUTHOR]

Herein we report the synthesis, characterization, photophysical and theoretical study of the luminescent dyad Ir‐RhB containing two emissive centers: The first fluorescent (RhB=rhodamine B) and the second phosphorescent (Ir=orthometalated iridium complex), bound with an aliphatic bridge. These nearly independent chromophores have triplet excited states which are very close in terms of energy, allowing for reversible energy transfer between them. The observed transient absorption spectra and their time dependent variations were interpreted in terms of a relatively simple kinetic model, where selective excitation of the iridium‐based chromophore affords the corresponding emissive triplet state, followed by its equilibration with the rhodamine based triplet state and simultaneous emissive relaxation to the dyad ground state. This model allows for analytical solution to give key characteristics of the dyad excited‐state dynamics, including the energy gap between these triplets (ΔE=0.017 eV) and the rate constant of energy transfer (k(Ir‐RhB)=6.0 ⋅ 108 s−1). These data were also verified by quantum chemical DFT and TD‐DFT calculations. [ABSTRACT FROM AUTHOR]

π‐Conjugated molecular materials often exhibit interesting photoluminescence, redox, and optoelectronic properties that grant them utility as light‐harvesting materials in solar cells, as the emissive component of organic light‐emitting diodes, and as fluorescence sensors. Preparing dye conjugates by appending multiple dyes together to generate π‐conjugated molecules is a common strategy to enhance the properties of these materials as it often imparts traits that cannot be achieved by the building blocks independently. Herein, we report molecular materials that incorporate boron difluoride hydrazone (BODIHY) and triphenylamine (TPA) units that exhibit charge‐transfer character, dual‐emission, and aggregation‐induced emission. The title compounds have low‐energy absorption bands (λabs=455–493 nm) that are red‐shifted relative to BODIHYs with smaller π‐systems and exhibit dual‐emission in the solution, solid, and aggregate states. TPA–BODIHY (donor‐acceptor) conjugates show multiple reversible redox events and, in combination, the data presented herein indicate that there is electronic communication throughout the donor‐acceptor and acceptor‐donor‐acceptor π‐systems. These results are rationalized with the use of computational chemistry and solid‐state structural analysis. This study provides new opportunities for the design of molecular materials that are comprised of redox‐active photoluminescent dyes, including BODIHY, and their potential applications. [ABSTRACT FROM AUTHOR]

Luminescence materials have gained extensive attention in anti‐counterfeiting owing to their unique superiorities. Visible‐near infrared (vis‐NIR) dual emission that combines naked‐eye visible light and concealed NIR light would provide a promising strategy for improving the covertness and secure anti‐counterfeiting effect. Here, two organic conjugated materials 4,4′‐(thieno[3,4‐c][1,2,5]thiadiazole‐4,6 diyl)bis(N,N‐bis(4‐(aldehyde)phenyl)aniline) (TTD‐TPA‐CHO) and 4,4′‐(thieno[3,4‐c][1,2,5]thiadiazole‐4,6 diyl)bis(N,N‐bis(phenyl)aniline) (TTD‐TPA) based on thieno[3,4‐c][1,2,5]thiadiazole (TT) have been developed, exhibiting vis‐NIR dual emissions by manipulating the charge transfer states. With the aid of self‐healing technique, stretchable and highly transparent TTD‐TPA‐CHO and TTD‐TPA containing self‐healing PDMS films are efficiently prepared to fabricate dual‐mode anti‐counterfeiting patterns for demonstrating the anti‐counterfeiting applications. Under UV light, the luminescent patterns in visible region can be read out by the naked eye, while the concealed information could be accessed by NIR detection devices. These results evidently suggest the important role of vis‐NIR dual emission in enhancing the stealth of encrypted information and the security level of anti‐counterfeiting. Hopefully, this work would promote the further development of vis‐NIR dual‐emission organic conjugated materials in anti‐counterfeiting techniques. [ABSTRACT FROM AUTHOR]

Dual emission light‐emitting dendrimers composed of phosphorescent fac‐tris[2‐phenylpyridyl]iridium(III) [Ir(ppy)3] cores and thermally activated delayed fluorescence‐based (TADF‐based) dendrons have been prepared. The TADF‐based dendrons are designed to have green or blue emission. The dendrimers show solvatochromism, with the emission switching between phosphorescence and TADF depending on the medium in which the measurement is undertaken. Time‐dependent photoluminescence (PL) spectra measurements show that the TADF dendrons can act as an energy pool for emission from the phosphorescent core. The PL quantum yields (PLQYs) are found to be strongly dependent on the dielectric constant of the solvent, ranging from as high as 76% to as low as 0.3%. Neat films of the dendrimers are found to have relatively balanced hole and electron mobilities of order 10–6 cm2 V–1 s–1, with bilayer organic light‐emitting diodes (OLEDs) containing neat emissive layers having a maximum external quantum efficiency (EQE) of 4.7% for a film having a PLQY of 12%. Finally, the solution processed OLEDs fabricated using 0.4 mol% of the dendrimers blended with 9‐[3‐(9H‐carbazol‐9‐yl)phenyl]‐9H‐carbazole‐3‐carbonitrile result in green emission with maximum EQEs of 9.8% and 15.1% for the dendrimers with green and blue emissive TADF dendrons, respectively. [ABSTRACT FROM AUTHOR]

Novel triarylmethanols and triarylmethyl cations with diphenylamino groups were designed and synthesized. The triarylmethyl cations exhibited near‐infrared (NIR) emission in toluene solution, solid film state, and polystyrene (PS) film. The emission intensities of the triarylmethyl cations were strongest in the PS film. The relative quantum yield of the PS film increased as the number of diphenylamino groups increased. In addition, triarylmethanols exhibit dual emission in their aggregated state owing to the intermolecular interactions between triphenyl amine moieties and/or hydroxy groups. These findings are interesting because NIR and dual emissions are not observed in the dimethylamino group‐substituted triarylmethyl cation, which is referred to as the "malachite green," and the corresponding triarylmethanol, respectively. [ABSTRACT FROM AUTHOR]

A B−N embedded nitrogen‐annulated perylene has been successfully synthesized. The resultant molecule BN−NP is isoelectronic to coronene, but owns a five‐membered pyrrole ring. Experiments and DFT calculations indicated that peripheral pyrrole and BN modifications endow BN−NP with various unique properties like bent structure, dual emission, efficient Lewis acidic response, peripheral aromaticity, narrowest energy band gap among all coronene isoelectronic structures and so on. [ABSTRACT FROM AUTHOR]

Fluorescent probes that exhibit solvatochromic or excited-state proton-transfer (ESPT) properties are essential tools for the study of complex biological or chemical systems. Herein, the synthesis and characterization of a novel fluorophore that reveals both features, 5-isocyanonaphthalene-1-ol (ICOL), are reported. Various solvatochromic methods, such as Lippert–Mataga and Bilot–Kawski, together with time-dependent density functional theory (TD-DFT) and time-resolved emission spectroscopy (TRES), were applied to gain insights into its excited-state behavior. To make comparisons, the octyloxy derivative of ICOL, 5-isocyano-1-(octyloxy)naphthalene (ICON), was also prepared. We found that internal charge transfer (ICT) takes place between the isocyano and –OH groups of ICOL, and we determined the values of the dipole moments for the ground and excited states of both ICOL and ICON. Furthermore, in the emission spectra of ICOL, a second band at higher wavelengths (green emission) in solvents of higher polarities (dual emission), in addition to the band present at lower wavelengths (blue emission), were observed. The extent of this dual emission increases in the order of 2-propanol < methanol < N,N-dimethylformamide (DMF) < dimethyl sulfoxide (DMSO). The presence of the dual fluorescence of ICOL in these solvents can be ascribed to ESPT. For ICOL, we also determined ground- and excited-state pKa values of 8.4 ± 0.3 and 0.9 ± 0.7, respectively, which indicates a considerable increase in acidity upon excitation. The TRES experiments showed that the excited-state lifetimes of the ICOL and ICON spanned from 10.1 ns to 5.0 ns and from 5.7 ns to 3.8 ns, respectively. In addition, we demonstrated that ICOL can be used as an effective indicator of not only the critical micelle concentration (cmc) of ionic (sodium lauryl sulfate (SLS)) and nonionic surfactants (Tween 80), but also other micellar parameters, such as partition coefficients, as well as to map the microenvironments in the cavities of biomacromolecules (e.g., BSA). It is also pointed out that fluorescence quenching by pyridine can effectively be utilized for the determination of the fractions of ICOL molecules that reside at the water–micelle interface and in the interior spaces of micelles. [ABSTRACT FROM AUTHOR]

A series of new platinum square planar complexes [Pt(NCN)L]+/0 with the pincer N^C^N cyclometallated ligand (NC(H)N = 1,3-bis(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)benzene) containing the following L: Cl−, acetonitrile, pyridine, dimethylaminopyridine, 2,6-dimethylphenylisocyanide, has been synthesized. Application of bridging acetate ion as L ligand allowed obtaining a binuclear [Pt(NCN)]2OOCCH3 complex. The bulky and rigid structure of N^C^N-ligand provokes instability of its pincer coordination that makes possible transformation of the molecular architecture to give a heteronuclear complex with the Pt-Ag-Pt coordination core. The composition and structure of the obtained compounds were characterized in solution and in the solid state using ESI mass-spectrometry, NMR spectroscopy, elemental analysis, and single-crystal XRD crystallography. The complexes luminesce in solid state, solution, and in polymeric matrix demonstrating moderate to bright emission at ca. 550 nm with quantum yields up to 22% and lifetime of excited state up to 22 µs. TD DFT computational approach together with analysis of the photophysical properties in different media reveals the predominant ligand-centered 3IL nature of the radiative excited state localized at the N^C^N-ligand. The ancillary ligand L demonstrates a minor influence on the energy of emission but affects dramatically emission efficiency and lifetime. The chloride complex displays dual (fluorescence and phosphorescent) luminescence due to labile coordination of an N-coordinated functionality that produces a dangling aromatic fragment, which gives emission from a singlet excited state.

Long-afterglow luminescent materials has undergone extensive research in sensing and anti-counterfeiting. However, the complex preparation process, single luminescence with low quantum yields, potential biological toxicity and harsh application conditions limited the widespread use of these materials. In this work, 3-APBA CDs@MA was obtained by 3-aminophenylboronic acid, sulfuric acid and melamine via a one-pot hydrothermal process. The as-designed 3-APBA CDs@MA exhibit dual emission with quantum yields of 15.74 % and lifetime of 1.39 s for thermally activated delayed fluorescence and 1.63 s for room temperature phosphorescence. The afterglow of carbon dots can be observed by the naked eye for about 24 s and 13 s after turning off the 365 nm UV lamp and visible light lamp, respectively. Furthermore, the as-obtained 3-APBA CDs@MA show potential for temperature sensing and advanced anti-counterfeiting. Visible light-excited carbon dots with dual emission long-afterglow were synthesized by 3-aminophenylboronic acid, sulfuric acid and melamine via one-pot hydrothermal method. The as-designed 3-APBA CDs@MA exhibits dual emission with room temperature phosphorescence and thermal activated delayed fluorescence, 15.74 % quantum yields, 1.39 s and 1.63 s lifetime (TADF and RTP, respectively).Then the as-obtained 3-APBA CDs@MA was applied in anti-counterfeiting and temperature sensing. [Display omitted] • A new type of dual emission long-afterglow carbon dots-MA composite (CDs@MA) via one pot hydrothermal method. • Afterglow CDs@MA can be excited by UV and visible light. • Afterglow with long lifetime and can be seen by naked eye about 24 s. • Afterglow of CDs@MA can be maintained under water or other organic solvents. • A method of regulating afterglow dual emission is proposed. [ABSTRACT FROM AUTHOR]