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Highly efficient and thermally stable nonlinear optical chromophores based on the same thiophene π-conjugation and tricyanofuran acceptor (TCF) possessing different isolation groups attached to electron-donating moiety have been synthesized and systematically investigated in this paper. Density functional theory (DFT) was used to calculate the HOMO–LUMO energy gaps and first-order hyperpolarizability (β) of these chromophores. These new chromophores showed excellent thermal stability with their decomposition temperatures all above 250 °C. Most importantly, the molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic (EO) coefficients (r 33 ) in poled polymers. The doped films-B containing 25 wt % chromophore F1 displayed an r 33 value of 52 pm/V at 1310 nm, and the doped films-C containing F2 showed a value of 91 pm/V at the concentration of 35 wt %. These values are all much higher than the traditional FTC chromophore (39 pm/V). These results revealed that the introduced isolation group can reduce intermolecular electrostatic interactions thus enhance the macroscopic EO activity. Besides, the position of the isolation group plays an equally important role in achieving the ultra large EO coefficients of materials. These properties, together with the good solubility, suggest the potential use of these new chromophores as advanced materials devices. [ABSTRACT FROM AUTHOR]

Organic electro-optic (EO) materials have been widely explored and used in the fabrication of microwave photonic devices. Their principal advantages are the follows: lower half-wave voltage, wider bandwidth, lower cost and more convenience of integration. Organic second order nonlinear optical (NLO) chromophores, as the core of the organic EO devices, define the key technological parameters: EO efficiency, long term stability, solubility and optical losses. In the present review article, the use of D–π–A chromophore molecules with polycyclic electron donors based on julolidinyl structure is reported and discussed. Significant improvement of electron donating ability and appropriate isolated effect are shown. Future perspectives of the application of such kind of NLO chromophores are considered. [ABSTRACT FROM AUTHOR]

• Oblique-incidence reflectivity difference(OIRD) signals characters wax appearance temperature and the rate of change of crystallization process. • OIRD detection reveals the different stages of wax formation process. • OIRD is suitability for in situ probing of wax precipitation of different crude oils. Considering the negative effects of wax precipitation during petroleum transportation on flow assurance and profit loss, in this study, oblique-incidence reflectivity difference (OIRD) analysis is demonstrated to be a powerful tool for the in situ analysis of wax precipitation. Based on the hybrid detection of waxy oil and natural cooling, we develop a detailed wax precipitation model for waxy oil and demonstrate that it can be used to predict actual precipitation features, which are amenable to experimental validation. The curve trend of the OIRD detection exactly reveals the wax formation process, including nucleation, growth, and crystallization. The efficiency of this technique is proven by the fact that the OIRD signals provide the detailed characteristics of the wax precipitation, which include not only the wax appearance temperature (WAT) but also the rate of change of the crystallization process. The advantage of distinguishing between the different stages of the complex wax crystallization process with time and amplitude is demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: A novel chromophore BDT–TCF with benzo[1,2-b:4,5-b′]dithiophene (BDT) unit as electron bridge was synthesized and characterized by UV–vis, NMR spectroscopy, and thermal analysis. It is the first time that BDT unit was introduced into NLO materials. The chromophore showed excellent solubility in most common solvents, and good thermal stability for practical applications. The second order nonlinear optical effect was measured by hyper Rayleigh scattering method. The diagonal hyperpolarizability β zzz of BDT–TCF was 8.2×10−28 and 9.3×10−29 esu in THF solvent and in PMMA polymer matrices, respectively. The potential NLO response indicates that BDT unit is a promising π-electron bridge and an excellent candidate for nonlinear optical devices. [Copyright &y& Elsevier]

Energy, information, and materials are the three main factors required for the survival and development of modern humankind, with energy being the cornerstone of all development. In recent years, self-powered devices have received widespread attention. As a new generation device, Triboelectric nanogenerators (TENGs) assembled from flexible materials possess the characteristics of flexible design, low-cost, stable output performance, etc., and can be widely used in wearable and self-powered medical detection sensors of human body. In this paper, flexible bromobutyl rubber (BIIR) and PET were used as friction materials, and assembled into arched vertical contact-separation triboelectric nanogenerators following various film formation and surface roughening treatments. The treatment and assembly methods of the friction materials were studied in order to obtain the best power generating effects. In addition, due to the biocompatibility and intrinsic antibacterial property of BIIR films, the fabricated triboelectric nanogenerator was also applied to wearable self-powered sensor equipment, proving its potential in the fields of identification and gait analysis. The manuscript described the triboelectric nanogenerators assembled by bromobutyl rubber (BIIR) and PET, which has intrinsic antibacterial performance and high force detection sensitivity. It can be used in wearable and self-powered sensors. [Display omitted] • Ÿ Intrinsic antibacterial BIIR films were prepared by electrospinning and assembled into wearable and self - powered TENG. • Ÿ The BIIR-based TENGs is capable of energy-harvesting and signal recognition for identification and gait analysis. • The BIIR-based TENGs are easy to prepare and have the potential for large-scale industrial production. [ABSTRACT FROM AUTHOR]

Compared with traditional inorganic second-order nonlinear optical (NLO) materials, organic second-order NLO materials have many advantages in bandwidth, dielectric constant, half-wave voltage, electro-optic (EO) coefficients, processability, and material cost. Due to their potential applications in telecommunications, computing, detection, terahertz generation, and construction of functional photonic crystals, organic NLO materials have been widely studied for several decades. Currently, the poling efficiency and long-term stability are the largest obstacles for the application of organic NLO materials. At the molecular level, these problems are mainly caused by the strong dipole–dipole intermolecular interactions between the NLO chromophores with D-π-A structures. In the molecular design of the polymer system, modification of the chromophores is considered to be an efficient pathway to solve this problem. Since 2009, many studies have been performed by our group to reduce the strong dipole–dipole intermolecular interactions between the chromophores. In this review, the development of organic NLO materials in recent years is summarized, including the following: 1) a brief introduction of organic second-order NLO materials, 2) the requirements of NLO materials for applications in devices, 3) optimization of the first-order hyperpolarizability of NLO chromophores, 4) the optimization of the chromophore loading parameters (N, ), and 5) improvements of the stabilities of organic NLO materials. • Organic second order NLO materials was briefly introduced. • Requirements of NLO materials for applications in devices were discussed. • Optimized method for first-order hyperpolarizability and loading parameters of chromophore were discussed. • Method for improving stability of organic NLO materials was included. [ABSTRACT FROM AUTHOR]

Abstract: A novel nunchaku-like organic second order nonlinear optical chromophore containing a D–π–A backbone and a rigid biphenylene unit was prepared. The UV–vis absorption spectra studies demonstrated that the large rigid structure could suppress dipole–dipole interactions effectively. The electro-optic coefficient of a poled film containing 20% wt of the new dye doped in amorphous polycarbonate afforded a value of 39 pm/V at 1310 nm. Compared with results obtained from a similar D–π–A chromophore without the rigid isolated group, the new dye gave better performance. Moreover, the electro-optic film prepared with the new dye gave greater temporal stability, compared to a similar D–π–A doped poled film that was reported previously. These results indicated that the introduction of a biphenylene group could effectively reduce the intermolecular electrostatic interactions and aid the alignment of the chromophores. [Copyright &y& Elsevier]

• Methyl thujate inhibited mycelial growth of Penicillium expansum and reduced its virulence on harvested fruit. • ROS accumulation and mitochondrial membrane potential abolishment were induced. • Loss of plasma membrane integrity and cytoplasmic content leakage were detected. Fungal infection causes severe diseases on fruits and vegetables, eventually leading to postharvest loss, and thus it is urgent to explore safe substances to control postharvest diseases and elucidate the underlying antimicrobial mechanisms. Here, it was found that a monoterpenoid substance, methyl thujate, was effective in inhibiting mycelial growth of Penicillium expansum and reducing its virulence on harvested fruit dose-dependently. Moreover, dual-fluorescence staining and flow cytometry assay suggested that methyl thujate significantly decreased cell vitality, impaired membrane integrity, induced ROS accumulation and abolished mitochondrial membrane potential in P. expansum. As a consequence, membrane peroxidation and cytoplasmic content leakages occurred. In summary, methyl thujate could inhibit mycelial growth of P. expansum and reduce its virulence on harvested fruit, which is promising for controlling postharvest decay. [ABSTRACT FROM AUTHOR]

Methyl thujate, a monoterpenoid substance, was effective in controlling postharvest gray mold caused by Botrytis cinerea on apple fruit, during application in aqueous solution. Methyl thujate strongly inhibited spore germination, germ tube elongation and mycelial spreading of B. cinerea in the culture medium, and the inhibition on fruit decay was closely correlated with methyl thujate concentrations. By means of propidium iodide and fluorescein diacetate staining, loss of membrane integrity and cell viability in B. cinerea was detected after methyl thujate treatment. Furthermore, methyl thujate led to cytoplasmic accumulation of reactive oxygen species, leakage of cellular constituents and variations in cell wall component deposition in B. cinerea hyphae, as the genes encoded subunits for NADPH oxidase were synergistically upregulated, whereas the genes involved in cell wall modeling and virulence responded differentially. Taken together, these data suggest that the mechanisms by which methyl thujate decreased fruit decay may be directly attributed to the induced ROS burst, breakdown of cell membrane integrity and loss of cytoplasmic contents from the hyphae. [ABSTRACT FROM AUTHOR]

This work reports the high-pressure and high-temperature (HP-HT) synthesis of pure monoclinic phase of GdNbO 4 :Bi 3+ phosphors. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, and IR spectra were utilized to characterize the synthesized phosphors. The crystal structure distortions operated by the pressure leads to tunable emission varying from blue to yellow. A small increase of the probability of non-radiative energy transfer with increase of pressure is observed. It is shown that the efficiency of the energy transfer process is dependent on pressure. The calculations of CIE chromaticity coordinates were performed. [ABSTRACT FROM AUTHOR]

Two novel bichromophores YL1 and YL2 based on traditional aniline chromophore YL were synthesized by Cu(I) catalyzed click-reaction and systematically investigated in this paper. The UV–Vis, electrochemical property, thermal stability and EO activity of these chromophores were systematically studied and discussed. These two bichromophores showed good thermal stability. Then nonlinear optical polymer films were fabricated by doping chromophores into polymethylmethacrylate (PMMA). The doped films containing bichromophores YL1 and YL2 showed r 33 values of 20 and 17 p.m./V at concentration of 25 wt% at 1310 nm. These values were respectively 2.85 times and 2.43 times of the EO activity of chromophore YL (7 p.m./V). High r 33 values indicated that the new structure of bichromophores YL1 and YL2 can reduce intermolecular electrostatic interactions, thus enhancing macroscopic EO activity. These properties suggested the potential use of the new bichromophores in nonlinear optical materials. [ABSTRACT FROM AUTHOR]

A series of high performance chromophores P1 P3, based on N -(4-dibutylaminophenyl) tetrahydroquinolinyl or julolidinyl donors, and phenyl-trifluoromethyl-tricyanofuran acceptors linked together via π-conjugation through thiophene or vinylene moieties as the bridges, have been designed and synthesized. Density functional theory (DFT) was used to calculate the HOMO-LUMO energy gaps and first-order hyperpolarizability (β) of these chromophores. Chromophores P1 and P3 had good thermal stabilities with glass transition temperature higher than 110 °C. Most importantly, the high molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic (EO) coefficients (r 33 ) in poled polymers with rational chromophore designs. In electro-optic activities, the poled films of P1/APC, P2/APC and P3/APC afforded r 33 values of 223, 283 and 278 pmV −1 , respectively, at 1310 nm at the doping concentration of 25 wt%, which showed significant enhancement over the similar EO polymer systems previously reported. [ABSTRACT FROM AUTHOR]

Two series of highly efficient nonlinear optical chromophores A1-C1 and A2-C2 based on the julolidinyl donors and tricyanofuran or phenyl-trifluoromethyl-tricyanofuran acceptors (CF 3 -Ph-TCF) linked together via π-conjugation through thiophene or pyrrole or tetraene moieties as the bridges, have been synthesized and investigated. The ultraviolet absorption, solvatochromic, thermal stabilities and electro-optic activities of these chromophores were systematically studied to illustrate structure-performance relationships within the six chromophores. All the chromophores exhibited good thermal stabilities with the decomposition temperatures (T d ) higher than 200 °C. Appropriate combination of the π-conjugated bridge, electron-donor and electron-acceptor as well as the isolated group in the chromophores plays an important role in achieving larger electro-optic activities. Exemplified by the chromophore A2 with CF 3 -Ph-TCF acceptor, it gave a very large r 33 value of 223 pmV −1 at 1310 nm at the doping concentration of 25 wt%. [ABSTRACT FROM AUTHOR]

Nonconventional luminophores without long conjugated structures have received increasing attention due to their outstanding biocompatibility, easy preparation, environmental friendliness, and potential applications in sensing and imaging. The phenomena of aggregation emission, such as concentration-enhanced emission, aggregation-induced emission, excitation-dependent luminescence, and prevailing phosphorescence, are caused by molecular conformation and molecular packing. Herein, we briefly review the traditional luminophores represented by fused aromatic rings, and introduce the revolutionary concept of aggregation induced emission (AIE) in non-traditional luminescence and its applications in optics, biology, and other fields. The concept of the AIE can be applied to understand this phenomena in the field of non-traditional luminescence, in which non-aromatic systems contain electron-releasing and withdrawing parts, such as amine, amide, nitrile, imine, hydroxyl, carbonyl, etc. Moreover, we also address two mechanisms of cluster triggered emission (CTE) and crosslink-enhanced emission (CEE). Based on the reviewed data, we can conclude that the electron overlap caused by aggregation and through-space conjugation (TSC) have a profound impact on unconventional luminescence. We believe that this review would serve as a useful guide to design and application of unconventional luminophores, while the current challenges and future perspectives are also discussed. • The article introduced the revolutionary concept of aggregation induced emission (AIE) in non-traditional luminescence and its applications in optics, biology, and other fields. • Two mechanisms of cluster triggered emission (CTE) and crosslink-enhanced emission (CEE) were discussed in the field of non-aromatic luminescence systems. • In general, the three theories (AIE, CTE, CEE) are attributed to intramolecular motion restriction (RIM), electron overlap caused by aggregation and through-space conjugation (TSC). • We believe that this review would serve as a useful guide to design and application of unconventional luminophores, while the current challenges and future perspectives are also discussed. [ABSTRACT FROM AUTHOR]

Abstracts In this work, a series of novel second order nonlinear optical chromophores modified by heteroatom-groups in electron-donor has been synthesized and systematically investigated. The resulting nonlinear optical chromophores exhibited both good thermal stability and good solubility in common organic solvents. UV–Vis spectra and density functional theory calculations were carried out to investigate the influence of heteroatom-groups on the electro-optic activities. The results revealed that increasing the electron-donor strength will not always improve the nonlinear optical activity of chromophore. There is a best match for electron-donor and acceptor. As to electro-optic activities, the doped polymer film- d3 displayed the highest electro-optic coefficient value of 37 pm/v at the doping concentration of 25 wt%. These results indicated that the nonlinear optical activities could be enhanced by finding the best match for electron-donor and acceptor in chromophore design. [ABSTRACT FROM AUTHOR]

A novel chromophore based on N -(4-dibutylaminophenyl)tetrahydroquinolinyl donor group was synthesized to compare with traditional chromophores based on either diethylaminophenyl or triarylaminophenyl donor groups. Cyclic voltammetry measurements showed that the new chromophore had a much smaller energy gap than the structurally related chromophores. Density functional theory calculations suggested that the molecular quadratic hyperpolarizability (μβ) value of tetrahydroquinolinyl chromophore is 65% and 110% larger than that of either the diethylaminophenyl or triarylaminophenyl chromophores, respectively. The doped film containing the tetrahydroquinolinyl chromophore showed an r 33 value of 126 pm/V at the concentration of 25 wt% which is much higher than the electro-optic activity of the diethylaminophenyl derived chromophore (39 pm/V) and six times higher than that of the traditional triarylaminophenyl chromophore (19 pm/V). The tetrahydroquinolinyl chromophore possesses much higher thermal stability (with its onset decomposition temperature above 280 °C) than those of commonly used alkyl chromophores. [ABSTRACT FROM AUTHOR]

Three novel nonlinear optical chromophores based on the same bis( N,N -diethyl)aniline donor have been synthesized and systematically characterized. These chromophores showed good thermal stability and chromophore y1 showed the best thermal stability of 249 °C. Besides, compared with the chromophore (y1) without the substituted group, chromophores y2 and y3 show better intramolecular charge-transfer absorption. Most importantly, the high molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic coefficients. The electro-optic coefficient of poled films containing 25% wt of chromophores y1–y3 doped in amorphous polycarbonate afforded values of 149, 138 and 157 pm/V at 1310 nm for chromophores y1–y3 respectively. These results indicated that the double donors of bis( N,N -diethyl)aniline unit can efficiently improve the electron-donating ability and the special structure can reduce intermolecular electrostatic interactions, thus enhancing the macroscopic electro-optic activity. These properties, together with good solubility, suggest the potential use of these chromophores as advanced materials. [ABSTRACT FROM AUTHOR]