Search

A novel acceptor–π–acceptor molecular rotor for the detection of viscosity was developed, and strategies for the design of ER-targeted two-photon excited fluorescent probes based on organic cations have been enriched.

Three novel donor-π-acceptor two-photon absorption compounds (1PZPy, 2PZIm, 3CZPy) bearing the 10-butyl-10H-phenothiazine (9-butyl-9H-carbazole) donor, the pyridinium (benzimidazolium) acceptor, and the 2,5-divinylthiophene π-bridge were synthesized and fully characterized by

A series of novel linear and V-shaped carbazole-based molecules functionalized by cyano acceptors and diversified donors (carbazole, diphenylamino, dimethylamino, methoxy, and ferrocene) were synthesized and characterized by hydrogen-1 nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, Fourier transform infrared spectroscopy, and high-resolution mass spectrometry. Their linear and nonlinear optical properties including UV–visible absorption, single-photon excited fluorescence, two-photon absorption, and frequency up-converted fluorescence, were systematically investigated in various solvents. The time-resolved photoluminescence studies using time-correlated single photon counting revealed their fluorescence lifetimes in THF. The solvent polarity exerts little effect on their absorption properties, while the emission properties (maximum fluorescence wavelength, Stokes shift, fluorescence quantum yield) display solvent polarity dependencies. Donor-acceptor functionalities and molecular dimensionality are considered to be the crucial structural factors that influence their optical properties. Pumped by a femtosecond laser (690–990 nm, 80 MHz, 140 fs), all the target molecules emit intense frequency up-converted fluorescence except FC1 and FC2 which contain one or two ferrocene donors. The two-photon absorption cross-sections in THF are in the range of 631–3014 GM. The density functional theory calculations were also conducted to unravel their electronic structures and to further understand the structure-property relationships. To our knowledge, this study is the first to be concerned with the single- and two-photon related photophysical properties of these D-π-A-π-D′ and D′-π-A-π-D-π-A-π-D′ carbazole-based molecules (D = donor, A = acceptor, π = conjugated bridge).

The optimal surgical modality for duodenal gastrointestinal stromal tumor (GIST) remains undefined. The purpose of this study was to evaluate long-term survival outcomes of patients who underwent radical resection (RR) or limited resection (LR) of duodenal GIST.A total of 325 patients identified from the Surveillance, Epidemiology and End Results (SEER) database who underwent surgery for duodenal GIST between 1986 and 2016 were classified into a LR group and a RR group based on the type of surgery received. Propensity score matching (PSM) was performed to minimize the selection bias in comparisons. Disease-specific survival (DSS) and overall survival (OS) were observed, and factors affecting the survival outcome were analyzed.In the entire cohort, 105 patients (32.3%) underwent RR and 220 (67.7%) received LR. Both the 5-year OS and DSS in RR group were significantly better than those in LR group (71.0% vs. 54.1%, P = 0.014; 66.6% vs. 49.1%, P = 0.025). PSM resulted in 95 pairs of patients, with long-term outcomes being comparable between the two groups. After adjusting covariates in the propensity matched cohort, the type of surgery still showed no significant impact on OS (hazard ratio [HR] 1.160; 95% confidence interval [CI] 0.662-2.033) and DSS (HR 1.208; 95% CI 0.686-2.128).Surgical modalities do not seem to have a significant impact on long-term survival outcomes of patients with duodenal GIST and should mainly depend on the tumor size and location.

Three novel two-photon absorption chromophores (1BI, 2TAZ, and 3PyB), which have trans-1,4-divinylbenzene π-bridge, methoxy donors, and different acceptors, were synthesized. Their structures were elucidated by means of hydrogen-1 nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, Fourier transform infrared spectroscopy, and high-resolution mass spectrometry. Their photophysical properties, including linear absorption, single-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated in various solvents. The structure-property relationships were studied aided with the density functional theory calculations. In addition, the absorption, single- and two-photon fluorescence spectra of 3PyB-ctDNA were examined to evaluate whether 3PyB could be used as a DNA stain. The possible interaction mechanism of 3PyB-ctDNA was also studied by the NaCl titration and the viscosity experiment. The results indicate that 3PyB may serve as a potential DNA fluorescent probe.

Four novel two-photon absorption compounds (1MOBI, 2MOHA, 3BrBI, and 4BrHA), which have assembled stilbene π-bridge, different electron acceptors and donors, were synthesized conveniently via the one-step Horner-Wadsworth-Emmons reaction. Their configurations are A-π-D-π-A, D′-π-D-π-D′, A′-π-A-π-A′, and D-π-A-π-D, respectively. Their linear and nonlinear optical properties including linear absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated in various solvents. The results demonstrate that the compounds with dihexylamino donors exhibit good optical properties. 2MOHA and 4BrHA exhibit large two-photon absorption cross-sections (2183 and 1737 GM) in DMF, which are larger than those of many known stilbene derivatives. The relationships between the structures and the optical properties were studied aided with the time-dependent density functional theory calculations.

A series of novel multipolar symmetric and asymmetric N–heterocyclic compounds with different configurations were designed and synthesized. Their structures were characterized by Fourier transform infrared spectroscopy, hydrogen−1 nuclear magnetic resonance, and mass spectrometry. Their photophysical properties including linear absorption, single–photon excited fluorescence, two–photon absorption, and two–photon excited fluorescence, were systematically investigated in various solvents. The relationships between the structures and the photophysical properties were studied aided with the density functional theory calculations.

A simple, rapid, and highly efficient method has been developed for the synthesis of a series of novel 1H-imidazo[4,5-f][1,10]phenanthroline derivatives (1BN, 2Py, 3BI, 4BT, and 5MOBI) via a three–component, one–pot reaction under solvent–free conditions. Their structures were characterized by FT–IR, 1H NMR, 13C NMR, MS, and elemental analysis. Their photophysical properties, including linear absorption, one–photon excited fluorescence, two–photon absorption, and two–photon excited fluorescence, were systematically investigated in various solvents. The results demonstrate that all the compounds emit relatively strong blue/cyan fluorescence. 1BN and 5MOBI exhibit large two–photon absorption cross–sections (471 and 654 GM) in THF. In addition, the relationship between the electronic structures and photophysical properties was investigated using density functional theory.

Four novel yellow-to red-emitting fluorophores with a 1-(2-hydroxyethyl) pyridinium core and different electron-donating terminal moieties (N-methylcarbazole, N,N-dibutylbenzenamine, N-methylpyrrole, and 2-methylfuran) were designed and facilely synthesized via the one-step Knoevenagel condensation. All these compounds (HPs) were characterized by 1H NMR, 13C NMR, and HRMS. Their photophysical properties including linear absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated in various solvents. And the density functional theory calculations were conducted to analyze the electronic structures of HPs. The two-photon absorption cross-sections (δ) values of HPs measured by the Z-scan technique were determined to be as large as 1354 (1HP-CZ), 4462 (2HP-BA), 836 (3HP-PR), and 2944 GM (4HP-FU) in DMSO. The two-photon action cross-sections (Φ × δ) values of 1HP-CZ and 2HP-BA in H2O measured by the two-photon induced fluorescence method were about 50 GM. 1HP-CZ, 3HP-PR, and 4HP-FU also exhibited good water solubility. Meanwhile, it was found that 2HP-BA exhibited notable aggregation-induced emission characteristic in DMSO/H2O mixture. The aggregate particle size distribution of 2HP-BA was measured by the dynamic light scattering method, and the aggregation characteristic of 2HP-BA was observed by the transmission electron microscopy. Besides, 2HP-BA also exhibited red emission. Then, HPs with relatively low cytotoxicity were used for one- and two-photon excited fluorescence imaging in living HepG2 cells. The results indicate that HPs are potential candidates in the bioimaging field due to their photophysical properties and biocompatibility.

Novel 2-substituted-4,5-diphenyl-1H-imidazoles (M1–M4) were synthesized via a three-component, one-pot reaction under solvent-free conditions. The structures were characterized by infrared, hydrogen-1 nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, mass spectrometry and elemental analysis. Their UV-visible absorption, single-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence were systematically investigated in different solvents. Pumped by femtosecond laser pulses, M1 and M4 exhibit large two-photon absorption cross-sections (585 and 1193 GM in DMF, respectively). The quantum chemical density functional theory calculations offer complementary information regarding the frontier orbitals and the molecular structures, which confirm that the degree of intramolecular charge transfer plays an important role in enhancing two-photon absorption properties.

The new donor-π-acceptor/acceptor-π-acceptor compounds ( FQQ , KZQ , JYQ , and LVQ ) were facilely synthesized and characterized by infrared, proton nuclear magnetic resonance, mass spectrometry, and elemental analysis. Their UV-visible absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence were systematically investigated in different solvents. The experiment results indicate that all these compounds exhibit relatively strong up-converted fluorescence and obvious solvatochromic effects. KZQ shows the largest σ value of 707 GM in THF upon 830 nm excitation. Its excellent optical properties provide a promising alternative as a polarity-sensitive two-photon fluorescent probe. Aided with the quantum chemical density functional theory calculations, the relationships between the structures and the properties were studied.

A series of novel asymmetric branched compounds that utilize a 1,3,5-triazine core and feature D-π-A-(π-D′-π-A′)0-2 configurations (D = donor, A = acceptor, π = conjugated bridge) were designed, successfully synthesized, and fully characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. Their photophysical properties including linear absorption, one-photon excited fluorescence, two-photon absorption, and frequency up-converted fluorescence, were systematically investigated in different solvents. With a rise in the polarity of solvents, the peak positions of the one-photon excited fluorescence are red-shifted and the Stokes shifts increase, while the linear absorption wavelengths change slightly. In addition, the target compounds except CZ show the positive solvatokinetic effect. With a rise in the number of branches, the red shifts of the absorption and emission maxima, the hyperchromicity of the molar absorption coefficients, and the decrease of the Stokes shifts are observed. The peripheral electron donors (carbazole, phenothiazine) and acceptors (pyridine, benzimidazole) also exert an important influence on the photophysical properties. Under excitation of 690–930 nm fs laser pulses, all the target compounds emit frequency up-converted fluorescence with the maximal peaks at 471–575 nm, and the two-photon absorption cross-sections in THF are 132 (PTZ), 182 (CZ), 453 (CZ-Py1), 844 (CZ-Py2), 1244 (CZ-BI1), and 2072 (CZ-BI2) GM, respectively. Their two-photon response is found to be nearly additive with respect to the number of branches. The time-dependent density functional theory calculations were conducted to gain an insight into their electronic structures and to better understand the structure-photophysical property relationships. The results clearly indicate the importance of appropriate structural units on the enhancement of two-photon absorption properties.

Three new acceptor–donor–acceptor compounds ( LBQ , DBQ , BYQ ) were synthesized and characterized by infrared, hydrogen nuclear magnetic resonance, mass spectrometry and elemental analysis. Their photophysical properties were investigated including linear absorption, single-photon excited fluorescence, fluorescence quantum yield and two-photon absorption. These compounds in CH 2 Cl 2 exhibit good fluorescence quantum yield which are 0.36, 0.26, and 0.25 and the largest two-photon absorption cross-section which are 48, 36, and 181 GM respectively. Under the excitation of Ti: sapphire laser with a pulse width of 140 fs, LBQ and DBQ emit blue two-photon excited fluorescence (TPEF), while BYQ emits bright yellow TPEF. BYQ has a good solubility in water and the σ can be as large as 130 GM, so it shows promising applications in many pharmaceutical and biological fields.

A novel poly(amide-urethane@imide) reverse osmosis (RO) composite membrane with chlorine-tolerant property was prepared on a polysulfone supporting film through two-step interfacial polymerization. The crosslinking agent – 5-choroformyloxyisophaloyl chloride (CFIC) was first reacted with 4-methyl-phenylenediamine (MMPD) via interfacial polymerization to get the nascent poly(amide-urethane) base membrane (CFIC–MMPD) without curing treatment. Then the resultant base membrane contacted again with the second aqueous solution containing functional secondary amine – N,N′-dimethyl-m-phenylenediamine (DMMPD) to obtain the poly(amide-urethane@imide) TFC RO membrane (MMPD–CFIC@CFIC–DMMPD). X-ray photoelectronic spectroscopy (XPS) was combined with attenuated total reflectance infrared (ATR-IR) to verify that the ultrathin polyimide film (CFIC–DMMPD) has been successfully grafted on the surface of the MMPD–CFIC base membrane. The images of scanning electronic microscopy (SEM) and atomic force microscope (AFM) showed that the poly(amide-urethane@imide) membrane has much smoother, more hydrophilic surface than the poly(amide/imide-urethane) membrane (MMPD/DMMPD–CFIC) prepared by conventional one-step interfacial polymerization of CFIC and composite MMPD/DMMPD. However, the permeation experiment revealed that the poly(amide-urethane@imide) membrane has a slight loss in both salt rejection and water flux than the poly(amide/imide-urethane) membrane and conventional commercialized polyamide membrane (MPD–TMC), but exhibits better chlorine-tolerant property due to the introduction of ultrathin polyimide film (CFIC–DMMPD) on the outmost surface of the TFC RO membrane, and the combination of IR and XPS analyses shows a good agreement with the chlorine exposure results of membranes.

Three nickel(II) complexes with phenanthroline-based ligands were synthesized and characterized by UV–visible, IR, MS, and elemental analysis. Their off-resonance third-order nonlinear optical (NLO)properties were measured using a femtosecond laser and the degenerate four-wave mixing technique. The third-order NLO susceptibilities χ (3) were 3.45–4.37 × 10−13 esu. The second-order hyperpolarizabilities γ of the molecules were 3.46–4.36 × 10−31 esu. The response times were 50–74 fs. The influence of the molecular structure on the third-order optical nonlinearity was analyzed. The results show that highly polarizable delocalized π-conjugated electron system is the key factor leading to strong third-order optical nonlinearity.

Three mixed ligand nickel(II) complexes were synthesized and characterized by UV–visible, IR, MS and elemental analysis. Their off-resonant third-order nonlinear optical properties were measured using femtosecond laser and degenerate four-wave mixing technique. The third-order nonlinear optical susceptibilities χ (3) were 3.20–3.51 × 10 −13 esu. The nonlinear refractive indexes n 2 were 5.89–6.45 × 10 −12 esu. The second-order hyperpolarizabilities γ of the molecules were 3.20–3.50 × 10 −31 esu. The response times were 55–81 fs. The results show that these complexes have potential nonlinear optical applications.

A new series of trans-alkenes (3a-3e) containing different electron-donating groups were synthesized by the solvent-free Horner-Wadsworth-Emmons reaction, and characterized by infrared, hydrogen nuclear magnetic resonance, mass spectrometry and elemental analysis. Their UV-visible absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence were systematically investigated in different solvents. Experimental results show different trends in linear and nonlinear optical properties with different donor units. 3a with triphenylamine donor exhibits the best optical properties. It emits strong blue up-converted fluorescence, and the two-photon absorption cross-section can be as large as 218 GM in DCM.

A series of all-trans acceptor–π-donor (acceptor) compounds (BAQ, SFQ, BLQ, and XJQ) were conveniently synthesised and characterised by infrared, nuclear magnetic resonance, mass spectrometry, and elemental analysis. Their photophysical properties, including linear absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated. All the compounds show obvious solvatochromic effects, such as significant bathochromic shifts of the emission spectra and larger Stokes shifts in more polar solvents. Under excitation from a femtosecond Ti : sapphire laser with a pulse width of 140 fs, they all exhibit strong two-photon excited fluorescence, and the two-photon absorption cross-sections in THF are 851 (BAQ), 216 (SFQ), 561 (BLQ), and 447 (XJQ) GM respectively. A combination of density functional theory (DFT) and time-dependent density functional theory (TDDFT) approaches was used to investigate the relationships between the structures and the photophysical properties of these compounds. The results show that they may have a potential application as polarity-sensitive two-photon fluorescent probes.

Three new acceptor–donor–acceptor branched compounds with triazine and benzimidazole units (M1, M2, and M3) were synthesized and characterized by infrared, hydrogen-1 nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, mass spectrometry, and elemental analysis. Their photophysical properties were investigated including linear absorption, single-photon excited fluorescence, fluorescence quantum yield, two-photon absorption, and frequency up-converted fluorescence. When the number of branches increases, the spectral positions of the linear absorption and the single-photon excited fluorescence show red shifts, while the fluorescence quantum yields decrease. When the polarity of solvents increases, the spectral positions of the single-photon excited fluorescence and the Stokes shifts also show red shifts, while the fluorescence quantum yields of the two-branched compound (M2) and three-branched compound (M3) decrease. Under the excitation of an 800 nm laser with a pulse width of 80 fs, all these compounds emit intense green frequency up-converted fluorescence, and the two-photon absorption cross-sections are 210, 968, and 1613 GM for M1, M2, and M3, respectively. This result shows that significant enhancement of the two-photon absorption cross-section can be achieved by sufficient electronic coupling between the strong charge transfer acceptor–donor–acceptor quadrupolar branches through the s-triazine core.