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Tetrahedral copper(I) clusters [Cu4(MBIZ)4(PPh3)2] (2), [Cu4(MBOZ)4(PPh3)4] (6) (MBIZ = 2-mercaptobenzimidazole, MBOZ = 2-mercaptobenzoxazole) were prepared by regulation of the copper-thiolate clusters [Cu6(MBIZ)6] (1) and [Cu8(MBOZ)8I]− (5) with PPh3. With the presence of iodide anion, the regulation provided the iodide-containing clusters [CuI4(MBIZ)3(PPh3)3I] (3) and [CuI4(MBOZ)3(PPh3)3I] (7). The cyclic voltammogram of 3 in MeCN (0.1 M nBu4NPF6, 298 K) at a scan rate of 100 mV s−1 shows two oxidation processes at Epa = +0.11 and +0.45 V with return waves observed at Epc = +0.25 V (vs. Fc+/Fc). Complex 3 has a higher capability to lose and gain electrons in the redox processes than complexes 2, 4, 4′, 6, and 7. Its thermal stability was confirmed by thermogravimetric analysis. The catalytic performance of 3 was demonstrated by the catalytic transformation of iodobenzenes to benzonitriles using AIBN as the cyanide source. The nitrile products show potential applications in the preparation of 1,3,5-triazine compounds for organic fluorescence materials. [ABSTRACT FROM AUTHOR]

Tetrahedral copper(I) clusters [Cu4(MBIZ)4(PPh3)2] (2), [Cu4(MBOZ)4(PPh3)4] (6) (MBIZ = 2-mercaptobenzimidazole, MBOZ = 2-mercaptobenzoxazole) were prepared by regulation of the copper-thiolate clusters [Cu6(MBIZ)6] (1) and [Cu8(MBOZ)8I]− (5) with PPh3. With the presence of iodide anion, the regulation provided the iodide-containing clusters [CuI4(MBIZ)3(PPh3)3I] (3) and [CuI4(MBOZ)3(PPh3)3I] (7). The cyclic voltammogram of 3 in MeCN (0.1 M nBu4NPF6, 298 K) at a scan rate of 100 mV s−1 shows two oxidation processes at Epa = +0.11 and +0.45 V with return waves observed at Epc = +0.25 V (vs. Fc+/Fc). Complex 3 has a higher capability to lose and gain electrons in the redox processes than complexes 2, 4, 4′, 6, and 7. Its thermal stability was confirmed by thermogravimetric analysis. The catalytic performance of 3 was demonstrated by the catalytic transformation of iodobenzenes to benzonitriles using AIBN as the cyanide source. The nitrile products show potential applications in the preparation of 1,3,5-triazine compounds for organic fluorescence materials.

Electron‐accepting units play vital roles in constructing donor‐acceptor (D‐A) conjugated organic optoelectronic materials; the electronic structures and functions of the acceptors need to be carefully unveiled to controllably tailor the optoelectronic properties. We have synthesized two D‐A conjugated organic fluorophores, TPA‐SO and TPA‐CO, with similar molecular skeletons based on sulfone‐ or carbonyl‐containing polycyclic aromatic acceptors. Both TPA‐SO and TPA‐CO display obvious solvent polarity‐dependent photophysical properties and large Stokes shift of over 100 nm for strong intramolecular charge transfer processes. Experimental evidence indicates that the sulfone group in TPA‐SO merely serves as a strong electron‐withdrawing unit. TPA‐SO shows yellowish‐green emission with a peak at 542 nm and an absolute photoluminescence quantum yield (PLQY) of 98 % in solution, whereas the carbonyl group in TPA‐CO can act as both an electron‐withdrawing unit and spin transition convertor, so TPA‐CO displays red emission with a low absolute PLQY of 0.32 % in solution. Impressively, upon going from solution to aggregate state, TPA‐SO nanoparticles keep a high PLQY of 9.5 % and moderate biocompatibility, thus they are good nano‐agents for cellular fluorescence imaging. The results reveal that the inherent acceptor characteristic acts as a crucial effect in the photophysical properties and applications of the organic fluorophores. [ABSTRACT FROM AUTHOR]

The value of two‐photon absorption cross‐section represents the effectiveness of simultaneous absorption of two incident photons. We reported a novel organic TPA material which has not reported before. It is an acceptor‐π‐donor‐π‐acceptor (A‐π‐D‐π‐A) idolizing pyridine compound 1, namely 3‐(pyridin‐2‐yl)‐N‐(3‐(pyridin‐2‐yl)indolizin‐1‐yl)indolizin‐1‐aminium perchlorate, (C26H20N5)⋅ClO4. The material can be easily synthesized in a one‐pot method with cheap materials. The compound 1 was structurally characterized through single‐crystal X‐ray crystallography, Hirshfeld surface, and spectroscopic techniques. Its photophysical properties were investigated. Compound 1 gives blue fluorescence and the lifetime of the emission peak in ethanol solution is τ=0.607 ns. The nonlinear absorption of the compound 1 solutions (in C2H5OH) was measured by the open‐aperture Z‐scan technique at a 532 nm wavelength. The results of Z‐scan experiments show that compound 1 has remarkable nonlinear optical absorption effects. The TPA cross‐section is δ=22583 GM. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel kind of hyperbranched polymers has been parepared by "click" chemistry. • A novel fluorescence materials were designed. • P1-Ln3+ could stain the cytoplasm in HeLa cells. Abstract Hyperbranched polymers have attracted increasing interest due to their unique properties which possess excellent RI and thermal stability, and have been widely used in fields of drug delivery, catalysts, liquid crystal and so on. Herein, polysiloxane-based hyperbranched fluorescent materials (P1 and P2) were synthesized by thiol-ene "click" chemistry. Then, novel polysiloxane-based hyperbranched fluorescent materials (P1-Ln3+) has been prepared by rare earth ions coordination. In view of the splendid fluorescence characteristics and favorable stability of P1-Ln3+ , it has been applied in biological imaging. P1-Ln3+ has gained commendable applications in bioimaging. [ABSTRACT FROM AUTHOR]

Studies on the following were reviewed: (1) the structure of spiropyrans and spirooxazines (two kinds of spiro compounds) under external stimuli and (2) the construction and applications of composite systems based on fluorescence resonance energy transfer (FRET) with fluorescent materials. When treated with different stimuli (light, acids and bases, solvents, metal ions, temperature, redox potential, and so on), spiropyrans/spirooxazines undergo transformations between the ring-closed form (SP), the ring-opened merocyanine (MC) form, and the protonated ring-opened form (MCH). This is due to the breakage of the spiro C-O bond and the protonation of MC, along with a color change. Various novel, multifunctional materials based on photochromic spiropyrans and spirooxazines have been successfully developed because of the vastly differently physiochemical properties posssed by the SP, MC and MCH forms. Among the three different structural forms, the MC form has been studied most extensively. The MC form not only gives complexes with various inorganic particles, biological molecules, and organic chemicals but also acts as the energy acceptor (of energy from fluorescent molecules) during energy transfer processes that take place under proper conditions. Furthermore, spiropyran and spirooxazine compounds exhibit reversible physicochemical property changes under proper stimuli; this provides more advantages compared with other photochromic compounds. Additionally, the molecular structures of spiropyrans and spirooxazines can be easily modified and extended, so better compounds can be obtained to expand the scope of already known applications. Described in detail are: (1) the structural properties of spiropyrans and spirooxazines and related photochromic mechanisms; (2) composite systems based on spiropyrans and spirooxazines, and (3) fluorescent materials which have potential applications in sensing, probing, and a variety of optical elements. [ABSTRACT FROM AUTHOR]

Copolymer of poly(styrene-co-n-caprylamide maleic acid) (PSCMA, defined as HL) and its lanthanide complexes Ln(L)·6HO (Ln = Eu and Tb) had been synthesized and characterized by elemental analysis, X-ray diffraction, Fourier transform infrared spectra, UV-spectrophotometer and thermal analysis (TG-DTA). The fluorescence properties of the HL ligand and the Ln(L)·6HO complexes in the solid state were investigated. At room temperature, the HL ligand had a strong broad emission band at 410-575 nm (λmax = 458 nm) under excitation at 380 nm, while the respective characteristic emission of Eu(III) and Tb(III) ions was observed in Ln(L)·6HO complexes. This demonstrated that the HL ligand in the extra-framework channels succeeded in sensitizing Eu(III) and Tb(III) ions emission. Compared with the Eu(L)·6HO complex, the fluorescence intensity of the Tb(L)·6HO complex was much stronger. This indicated that the lowest excited triplet state energy level of HL matched well with the excited state energy level of Tb(III). With the increase of the Ln(III) ions content below 15 wt%, the fluorescence intensity increased monotonically. All the Ln(L)·6HO complexes exhibited high quantum yield, long fluorescence lifetime and good thermal stability. [ABSTRACT FROM AUTHOR]

Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source. The experiment of the emission and excitation optical spectrum, decay curve of fluorescence and residuals for several sensitive materials confirms the match of YOS:Eu using the light source and the feasibility of the system. The rare earth material YOS:Eu is selected as the material candidate for being the most sensitive. [ABSTRACT FROM AUTHOR]

Dynamic fluorescence patterns with variable output in response to external stimulus can make the current information storage technologies more flexible and intelligent. Yet it remains a great challenge to create such dynamic patterns because of the complicated synthesis process, high cost, limited stability, and biocompatibility of the functional fluorophores. Herein, a facile approach is presented for creating dynamic fluorescence patterns using the photodynamic surface chemistry based on disulfide bonds. By this method, high-resolution (≈20 µm) multicolor dynamic fluorescence patterns that are low-cost and dynamically rewritable can be easily fabricated using classical fluorophores such as fluorescein, rhodamine, and dansyl acid. Owing to the spatio-temporal controllability of light, the fluorescence patterns can be partly or entirely erased/rewritten on demand, and complex gray-level fluorescence images with increased information capacity can be easily generated. The obtained fluorescence patterns exhibit little changes after storing in air and solvent environments for 100 days, demonstrating their high stability. In addition, static patterns can also be created on the same disulfide surface using irreversible disulfide-ene chemistry, to selectively control the dynamicity of the generated fluorescence patterns. The authors show the successful application of this strategy on information protection and transformation., (© 2021 Wiley-VCH GmbH.)

In this paper, we report the compound [((nBu) 4 N) 3 ][Tm(SCN) 6 ] (1), (nBu = CH 3 CH 2 CH 2 CH 2) undergoes a reversible structural phase change. • The high and low temperature structure of compound 1 was successfully resolved. • The compound 1 undergoes a reversible structural phase transition near 204 K. • 1 exhibits blue fluorescence (with λem = 458 nm) at room temperature. Thulium(III) chloride hydrate with potassium thiocyanate and tetrabutylammonium chloride formed a novel compound [((nBu) 4 N) 3 ][Tm(SCN) 6 ] (1) , (nBu = CH 3 CH 2 CH 2 CH 2) in the ratio 1:6:1. Differential scanning calorimetry (DSC) measurements show a pair of reversible peaks at 204.6 K (heating) and 188.7 K (cooling) with a heat hysteresis about 15.9 K, indicating the compound 1 undergoes a reversible structural phase change. Dielectric measurement further confirms the phase transition. X-ray single crystal diffraction analysis shows that the compound 1 belongs to triclinic crystal system in P −1 space group at temperatures of 140 K and 300 K, suggesting the phase transition is isosymmetric Zhang et al. (2013) [1]. The analysis of structure reveals that the disorder of the [(nBu) 4 N]+ cation, leading to the reversible structural phase transition. The results of solid-state fluorescence show that the emission peak of compound 1 is 458 nm, and which is of great significance to the development the fluorescence materials of the rare earth organometallic compounds. [ABSTRACT FROM AUTHOR]

A novel bis-4Ph-substituted 9,10-dipehnylanthracene deep blue [1931 CIE (0.15, 0.08)] fluorescent compound, AnB4Ph , has been synthesized and characterized for organic light-emitting diode (OLED) applications. Our experimental study of AnB4Ph excludes the possibility of triplet-triplet annihilation, hybridized local and charge transfer, or thermally activated delayed fluorescent characteristics of the material. Since the solid-state photoluminescence quantum yield of AnB4Ph was determined to be 48%, assuming a 100% for the charge recombination efficiency, the light outcoupling efficiency (η out ) of an AnB4Ph non-doped OLED achieving an external quantum efficiency (EQE) of 5.3% is at least 44%, which is more than twofold higher than 20% for conventional OLEDs. Both grazing incidence wide-angle X-ray scattering (GIWAXS) and angle-dependent photoluminescence (ADPL) measurements reveal AnB4Ph having a high value of order parameter ( S GIWAXS ) of 0.61 for a ππ stacking along the normal direction and an orientation order parameter ( S ADPL ) for a horizontal emitting dipole moment of -0.50 or Θ (horizontal-dipole ratios) of 100%, respectively. Otherwise, a refractive index ( n ) measurement provides a n = 1.80 for AnB4Ph thin films. Based on η out = 1.2 × n -2 , the calculated η out is 37%, which is also in accordance with the results of GIWAXS and ADPL. We have also fabricated the classical fluorescent DPAVBi -doped AnB4Ph OLEDs, which display a true blue [1931 CIE (0.15 and 0.16)] electroluminescence with a high efficiency (EQE = 6.9%), surpassing the conventional ∼5% EQE. Based on an η out of 42% for DPAVBi -doped AnB4Ph OLEDs, our studies suggest that the extremely horizontally aligned AnB4Ph host material exerts the same horizontal alignment on the DPAVBi dopant molecules.

Fluorescence imaging via carbon dots (CDs) has found multifarious applications in the biomedical sciences including biosensing, cancer cell bioimaging, drug delivery and tracking therapeutic response. Presently, the latest generation of fluorescence CDs known as green-CDs has attracted ever-increasing attention due to the use of natural sources, low-cost synthesis, nanoscale size, promising biocompatibility, superior photoluminescence, and ease of functionalization for versatile applications, which in turn could have higher priority over the traditional toxic fluorescent agents. In this review, we aim to have a new insight into the engineering green-CDs and their physicochemical properties. Moreover, we discuss the possible applications of green-CDs in self and active targeting, therapeutics delivery, and finally their promising future in cancer theranostics. Image 1 • The role of fluorescent green-CDs to guide therapy and monitoring the therapeutic response (Therapeutic). • Image-guided active and self-targeting of cancer cells via green-CDs (Diagnostic). • Future prospects of the green-CD application as a platform to integrate diagnostics and therapeutics (Theranostic). [ABSTRACT FROM AUTHOR]

During the last few years, the preparation of bifunctional fluorescent probes, which exhibit differential response towards multiple analytes, has attracted considerable attention since they are cost-effective and highly desirable for real-time applications. This review focuses on the recent advances in the design principles, recognition mechanisms, and applications of multifunctional fluorescent probes for the differential detection of multiple guests., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Studies on the following were reviewed: (1) the structure of spiropyrans and spirooxazines (two kinds of spiro compounds) under external stimuli and (2) the construction and applications of composite systems based on fluorescence resonance energy transfer (FRET) with fluorescent materials. When treated with different stimuli (light, acids and bases, solvents, metal ions, temperature, redox potential, and so on), spiropyrans/spirooxazines undergo transformations between the ring-closed form (SP), the ring-opened merocyanine (MC) form, and the protonated ring-opened form (MCH). This is due to the breakage of the spiro C-O bond and the protonation of MC, along with a color change. Various novel, multifunctional materials based on photochromic spiropyrans and spirooxazines have been successfully developed because of the vastly differently physiochemical properties posssed by the SP, MC and MCH forms. Among the three different structural forms, the MC form has been studied most extensively. The MC form not only gives complexes with various inorganic particles, biological molecules, and organic chemicals but also acts as the energy acceptor (of energy from fluorescent molecules) during energy transfer processes that take place under proper conditions. Furthermore, spiropyran and spirooxazine compounds exhibit reversible physicochemical property changes under proper stimuli; this provides more advantages compared with other photochromic compounds. Additionally, the molecular structures of spiropyrans and spirooxazines can be easily modified and extended, so better compounds can be obtained to expand the scope of already known applications. Described in detail are: (1) the structural properties of spiropyrans and spirooxazines and related photochromic mechanisms; (2) composite systems based on spiropyrans and spirooxazines, and (3) fluorescent materials which have potential applications in sensing, probing, and a variety of optical elements., Competing Interests: The authors declare no conflict of interest.