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Alkyl chain-resulted odd-even effects in fluorescence quantum yield (FLQY) have also been reported in organic luminescent materials (OLMs). However, the odd-even effects in FLQY caused by the alkyl substitutes in OLMs are generally very weak, with only single-digit differences. Here, we report a series of alkyl-substituted dual-state luminogens (DSEgens) showing extremely high solid-state FLQY in even-numbered analogues (90% FLQY) and a dramatically pronounced odd-even effect in FLQY. The odd-even effect in FLQY is over 26% alternation, and a maximum of 48% difference in FLQY was observed between the compounds

Cyanostilbene and naphthalimide are incorporated to construct novel dual-state emission luminogens (DSEgens), which show highly efficient photoluminescence and two-photon absorption properties in both dilute solution and the aggregated state.

The fusion of multiple rigid, planar units into a highly twisting molecule is proposed as a molecular engineering strategy for synthesizing bright dual-state emitters. Applications such as mechanosensor and fluorescent probe have been demonstrated.

Two α-cyanostilbene derivatives exhibiting bright emission in both well-dissolved solutions (Φ > 49%) and the solid state (Φ > 95%) have been synthesized as novel DSEgens for high-contrast mechanofluorochromism (>50 nm) and live cell imaging.

Luminogens with distinct photophysical properties were synthesized by attaching TPE and TPA on a saturated cyclohexyl ring in an isolated fashion, demonstrating the effectiveness of the concept of “aryl isolation” in engineering AIEgens and DSEgens.

A new family of imidazole-based AIEgens has been synthesized as fluorescent probes for specific recognition of picric acids over a variety of nitroaromatic compounds in aqueous media with high sensitivity.

A novel tetraphenylethylene (TPE)-functionalized arylimidazole derivative (HTPEAIM) has been designed and synthesized. The structure was characterized by FT-IR, HR-MS, 1H and 13C NMR. The photophysical properties were investigated by UV–vis absorption and PL spectra. HTPEAIM exhibited excellent aggregation-induced emission (AIE) property that it was non-emission in organic solution and with high fluorescence in aggregation state as the restriction of intramolecular motions (RIMs). Moreover, HTPEAIM could be a fluorogenic probe for sensing picric acid (PA) and Cu2+ in the aqueous environment. Since the proton binding capacity of the N atom of the imidazole group and the donor–acceptor interactions, HTPEAIM was able to sensitively and selectively detect PA through the synergistic effects of photoinduced energy transfer (PET) and fluorescence resonance energy transfer (FRET) with a limit of detection (LOD) of 0.99 μM. Meanwhile, driving by the metal binding ability of the pincer-like structure of hydroxyl and imidazole group, HTPEAIM was used for sensing Cu2+ in the aqueous environment. The response mechanism was systemically studied, and the results showed that the stable Cu(HTPEAIM)2 complex was formed and that induced the fluorescence highly quenching to obtain a low LOD of 34.8 nM.

Tetraphenylethylene functionalized arylimidazole derivatives G4, G3, G2, L-G4, L-G3 and L-G2 with different substituent groups and geometric structures have been designed and synthesized. All the compounds exhibited excellent aggregation-induced emission (AIE) properties due to the restricted intramolecular rotation (RIR) and the formation of J-aggregates. The solid compounds showed highly efficient emission with fluorescence quantum yields (ΦPL) of 67%, 72%, 67%, 40%, 52% and 48% for G4, G3, G2, L-G4, L-G3, and L-G2, respectively. The structure–property studies revealed that G4, G3 and G2 were more twisted structures and L-G4, L-G3 and L-G2 were partially planar conformations. The high quantum yields of the six solid compounds were driven by the synergistic effects of intramolecular electron transfer, molecular configuration and intermolecular interactions. On the other hand, the compounds also showed mechanochromism, acidochromism and picric acid-sensing properties. The compounds presented reversible mechanochromic behaviors between green and yellow emission and maintained highly solid emission (ΦPL about 50%) after grinding. The ΦPL values of the twisted molecules of G4, G3, and G2 decreased about 20% and those of the planar compounds showed a negligible change, which could be explained by the molecular structure planarization and the increased intermolecular interactions after grinding. Meanwhile, due to the excellent proton-binding properties of the imidazole group and pyridine group, the compounds were used as picric acid (PA) sensors with high selectivity and sensitivity in aqueous media and acid/base switches. The relative mechanism was ascribed to the photo-induced electron transfer (PET) and protonation, which were verified by 1H NMR spectra and theoretical calculations.

Controlling the fluorescence properties of organic molecules in the aggregation state and understanding the structure–activity relationship are important for developing excellent luminophors with tunable solid emission. Herein, a series of carbazole based donor/acceptor (D/A) type fluorophores functionalized with different substituents (–N(CH3)2, –H, –Br, –CN) were designed and synthesized. The optical measurements show that the compounds exhibit unique solid luminescence because the substituents influence the aggregated packing mode. Interestingly, the compounds CZ–H, CZ–Br, and CZ–CN with –H, –Br, and –CN substituents display aggregation-induced emission (AIE) originating from the restriction of the molecular vibration and rotation. The compound CZ–N with the –N(CH3)2 substituent exhibits crystallization-induced emission (CIE) derived from the packing differences and an increase in crystallinity from amorphous to crystalline states. Furthermore, the N-butylcarbazole unit of CZ–N, CZ–H, CZ–Br and CZ–CN was replaced by the N-bromidebutylcarbazole unit to obtain the corresponding polybromide compounds Br–CZ–N, Br–CZ–H, Br–CZ–Br, and Br–CZ–CN. Notably, the solid emission of these four compounds is largely red-shifted to longer wavelength regions (λFL = 558–618 nm) compared to those without a bromide substituent in the N-butyl chain of carbazole, owing to the bromine induced unique molecular conformation and packing arrangements in the aggregation state. Moreover, because of the diverse fluorescence properties of the eight compounds in various aggregated forms, they exhibit reversible fluorescence response to the transition of solid phases between crystalline and amorphous states under the mechanical force stimuli through breaking the multi-intermolecular interactions.

Developing dual-state fluorescence materials with high emission efficiency both in solution and solid states is still a challenge. Herein, a functionalized pyrazoline derivative (NF) was designed and synthesized. NF exhibited high blue emission efficiency in both THF solution and solid states with the absolute fluorescence quantum yields of 58% and 43%, respectively. The mechanism of this unique fluorescence behavior was systematically studied with the help of single-crystal structure analysis. The results showed that a close-knit molecular structure existed due to intramolecular C–H⋯π interactions, which can impair the intramolecular rotation to accelerate the radiative transition in the mono-molecule state (in dilute solution). Moreover, the steric hindrance and intermolecular hydrogen-bond interactions of the substituent groups can restrict the close packing and prompt the formation of J-aggregates in the aggregation state, which resulted in high emission performance in the solid state. Meanwhile, the dual-state blue emission property of NF was utilized for the picric acid (PA) detection in the solution state and on a test paper by the synergistic effects of photo-induced electron transfer (PET) and Forster resonance energy transfer (FRET) processes. The limit of detection as low as 6.80 × 10−7 M achieved in the THF–H2O mixture. This work provided a new scope for the design of high dual-state blue emission materials.

A novel difluoroboron fluorophore with an electron donor–acceptor conjugated structure was synthesized with 26.5% fluorescence quantum yield, 18 035 GM two-photon absorbing cross-section, and undetectable two-photon fluorescence, resulting in 25% 1O2 quantum yield. The unique optical behavior of CNFBBN enabled one-photon fluorescence imaging and two-photon phototherapy against HeLa cancer cells, irradiated at separate wavelengths.

Two novel carbazole derivatives containing tetraphenylethylene and cyano groups have been synthesized and characterized. The only difference between TPECZ and TPECZBr is at the C-8 and C-1 positions with or without a Br atom. Interestingly, they exhibited similar photophysical properties in solution, while their quantum yields and molecular packing models in solid state were significantly different. It was confirmed by single crystal structure analysis that the presence of a Br atom changed the molecular packing. Meanwhile, the two compounds exhibit mechanochromism (MC) behaviors, that the fluorescence emissions can be changed between yellow and orange. The powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) suggested that the MC mechanism of TPECZ and TPECZBr can be correlated with a phase transition between crystalline and amorphous states.

Detection of nitroaromatic explosives especially picric acid (PA) is considerably worth concern on human safety and homeland security. Herein, we developed an effective probe (APPTPEP) for PA detection in aqueous medium by combination of 1,4-dihydropyrrolo[3,2-b]pyrrole with tetraphenylethylene and pyridine units. The incorporation of tetraphenylethylene unit in the backbone endows the APPTPEP a significant aggregation induced emission (AIE) behavior. Pyridyl group was proved as recognition site for PA and their strong interaction was confirmed by 1H NMR titration and supported by theoretical calculation. Owing to this strong affinity, APPTPEP exhibited high selectivity and sensitivity (limit of detection 31.5 nM) to PA over other nitroaromatic compounds. This research provides new insights into the rational design of AIE-active materials for effective sensing application.

Five quinoline derivatives containing different alkyl chains (QLACn, n = 2, 4, 6, 8, 12) were synthesized to investigate the effect of alkyl chains on their photophysical properties. The fluorescent properties of the QLACn were affected by the alkyl chains, which indicated obvious blue-shifting trend and fluorescence emission are alkyl chains length-dependent by grinding-induced spectral shifts (ΔλMFC). Longer alkyl-length revealed larger ΔλMFC. Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) measurements indicated that the transformation between microcrystalline and amorphous states upon external stimuli should be responsible for the observed reversible MFC behavior.

Germin-like proteins (GLPs) play important roles in plant disease resistance but are rarely reported in cotton. We compared the expression of GLPs in Verticillium dahliae inoculate G. hirsutum (susceptible) and G. barbadense (resistant) and enriched 11 differentially expressed GLPs. 2741 GLP proteins identified from 53 species determined that GLP probably originated from algae and could be classified into 7 clades according to phylogenetic analysis, among which Clade I is likely the most ancient. Cotton GLP (two allopolyploids and two diploids) genes within a shared clade were highly conserved. Intriguingly, clade VII genes were mainly located in gene clusters that derived from the expansion of LTR transposons. Clade VII members expressed mainly in root which is the first battle against Verticillium dahlia and could be induced more intensely in G. barbadense than G. hirsutum. The GLP genes are resistant to Verticillium dahliae, which can be further investigated against Verticillium wilt.

Study Design Retrospective and prospective cohort study. Objectives Survival estimation is necessary in the decision-making process for treatment in patients with spinal metastasis from cancer of unknown primary (SMCUP). We aimed to develop a novel survival prediction system and compare its accuracy with that of existing survival models. Methods A retrospective derivation cohort of 268 patients and a prospective validation cohort of 105 patients with SMCUP were performed. Univariate and multivariable survival analysis were used to generate independently prognostic variables. A nomogram model for survival prediction was established by integrating these independent predictors based on the size of the significant variables’ β regression coefficient. Then, the model was subjected to bootstrap validation with calibration curves and concordance index (C-index). Finally, predictive accuracy was compared with Tomita, revised Tokuhashi and SORG score by the receiver-operating characteristic (ROC) curve. Results The survival prediction model included six independent prognostic factors, including pathology ( P < .001), visceral metastases ( P < .001), Frankel score ( P < .001), weight loss ( P = .005), hemoglobin ( P = .001) and serum tumor markers ( P < .001). Calibration curve of the model showed good agreement between predicted and actual mortality risk in 6-, 12-, and 24-month estimation in derivation and validation cohorts. The C-index was .775 in the derivation cohort and .771 in the validation cohort. ROC curve analysis showed that the current model had the best accuracy for SMCUP survival estimation amongst 4 models. Conclusions The novel nomogram system can be applied in survival prediction for SMCUP patients, and furtherly be used to give individualized therapeutic suggestions based on patients’ prognosis.

A novel difluoroboron derivative (TPEBF) containing α-cyanostilbene and tetraphenylethylene units has been designed and synthesized. TPEBF emits strong fluorescence both in dilute solutions (ΦFL = 19.3% in THF) and in the solid state (ΦFL = 49.3%), which is significantly distinct from the case of the aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE) chromophores. The dual-state emission properties of the compound overcome the limitation of single-state luminescence and enable it to be used in both solid and solution states. TPEBF with strong emission in solution is utilized for sensing picric acid (PA) with high selectivity and sensitivity in THF (LOD = 497 nM) and aqueous media (LOD = 355 nM). The mechanism was described for the synergy of fluorescence resonance energy transfer (FRET) and photoinduced energy transfer (PET) based on the UV-vis absorption and fluorescence spectra, 1H NMR and theoretical calculations results. On the other hand, the highly efficient emission in the solid state allows the compound to be cast on paper to switch external acid/base stimuli.

TD-DFT quantum calculation was performed to predict and/or illustrate the electronic transition, the related absorption and emission maxima of some pyrrole-difluoroboron derivatives with different electron donor–acceptor unit or π-conjugated degree. Upon the calculated results, a new near infrared (NIR) fluorophore (abbreviated as TPBD-BP) was designed and fabricated through linking triphenylamine and pyrrole-difluoroboron units to benzothiadiazole (BTD) backbone. The fluorescence of TPBD-BP in solid state centered at 932 nm, which was 985 nm for TPBD-BP nanoparticles (TPBD-BP dots) encapsulated in PEG-6000. The fluorescence of TPBD-BP in both solid state and dots exhibited off-peak tail emission to NIR-II region (extended to 1300 nm). The TPBD-BP dots showed excellent water solubility, biocompatibility and aggregation induced emission (AIE), which was suitable to be applied in vivo imaging. NIR-II emission signal of TPBD-BP dots can be observed in the reproductive organ of normal nude mice after tail vein injection. This attractive combination of computational and experimental investigation would help to develop new-typed small-molecular NIR fluorophores.

Background Many studies have investigated heavy metal exposure could increase the occurrence of congenital heart defects (CHDs). However, there are limited data regarding the relationship between cobalt exposure and CHD occurrence in offspring. The aim of this study was to analyze the association between cobalt exposure in mothers and the risk of CHDs in offspring. Materials and methods In order to explore the association between cobalt exposure and occurrence of congenital heart defect (CHD), a case-control study with 490 controls and 399 cases with CHDs in China were developed. The concentrations of cobalt in hair of pregnant woman and fetal placental tissue were measured and processed by a logistic regression analysis to explore the relationship between cobalt exposure and risk of CHDs. Results The median concentration of hair cobalt in the control and case group was 0.023 ng/mg and 0.033 ng/mg (aOR, 1.837; 95% CI, 1.468–2.299; P < 0.001), respectively. And the median (5–95% range) fetal placental cobalt concentrations were 19.350 ng/g and 42.500 ng/g (aOR, 2.924; 95% CI, 2.211–3.868; P < 0.001) in the control and case groups, respectively. Significant differences in the middle level of cobalt in hair were found in the different CHD subtypes, including septal defects, conotruncal defects, right ventricular outflow tract obstruction, and left ventricular outflow tract obstruction (P < 0.001). Dramatically, different cobalt concentrations in fetal placental tissue were found in all subtypes of cases with CHDs (P < 0.01). Conclusions The finding suggested that the occurrence of CHDs may be associated with cobalt exposure.

In this study, a terpyridyl derivative 2-(6-(pyridin-2-yl)-4-(4-((E)-2-(pyridin-4-yl)-vinyl)phenyl)pyridin-2-yl)pyridine (abbreviated as PYTPY) has been designed and prepared with an A–π–A architecture (A = electron acceptor), whose spontaneous aggregation style can be triggered by different external conditions. Mathematical modelling through time dependent density functional theory (TD-DFT) provides a quantitative understanding of the equilibrium molecular geometries at the aggregated state between adjacent PYTPY molecules with addition of different additives, such as water, H+, and Ag+ ions. The vertical electronic excitations and the related UV-vis absorbing character of PYTPY under different conditions were also forecasted, which was verified by the examined absorption spectra. Our method of calculating intermolecular interactions between adjacent molecules and predicting spontaneous aggregation style and absorption performance under an external environment is generally applicable to design and create other functional organic materials.

Three new D-π-A quinoline derivatives (G1, G2 and G3) were synthesized by facile methods. The three obtained ICT molecules revealed evident solvatochromic effect. Importantly, G1 and G2 can be effectively applied as powerful tools for PA detection in the monomer state with low limits of detection (LOD). The fluorescence quenching by PA can be attributed to the obstruction of ICT process in the quenching process. In solid-state, owing to reversible transformation by protonation and deprotonation, the three compounds exhibited excellent acid–base switching. Meanwhile, six compounds containing different anions (G2a, G2b, G2c, G2d, G2e, G2f) based on G2 were obtained by anion regulation in methanol. Importantly, the findings demonstrated distinct differences in the solid-state fluorescence of these compounds. These differences may arise from controlling anions to form different molecular packing arrangements.

A multi-functional nanohybrid (PyAnOH-Ag) with both a two-photon photothermal therapy (TP-PTT) effect and two-photon excited fluorescence (TPEF) imaging performance has been fabricated based on interfacial coordination interactions. The hybrid possesses a high two-photon absorption cross section (δTPA, 4638 GM) and detectable TPEF signals, which leads to excellent two-photon photothermal conversion. Upon irradiation at 840 nm, the temperature of the PyAnOH-Ag-PBS suspension reaches 42 °C in just 4 min, which results in 80% photothermal toxicity on HepG2 cells. The detectable TPEF signals can be used to monitor the cell ablation procedure. Moreover, PyAnOH-Ag exhibits a good phototherapeutic effect on tumor tissue of H22-modelled mice with almost 100% tumor growth inhibition under 840 nm irradiation for 10 min, which is superior to many reported photothermal agents. This strategy of TPEF guided TP-PTT agents can be potentially applied in a variety of therapeutic agents with monitoring ability.

Two novel α-cyanostilbene derivatives bearing triphenylamine and BF2 groups are synthesized (named TPE-B and TPE-BN). The fluorescent emissions of compounds TPE-B and TPE-BN are hypochromatically shifted and bathochromically shifted, respectively, with increasing polarity of the solvents, suggesting that the two compounds have characteristic polarity-dependent solvatochromic effects. Furthermore, they show obvious aggregation-induced emission enhancement (AIEE) phenomenon in THF/water mixture solutions. Meanwhile, compounds TPE-B and TPE-BN emit orange and yellow fluorescence in their solid states, respectively. Most significantly, in aqueous medium, compounds TPE-B and TPE-BN can selectively and sensitively detect picric acid (PA) among a number of nitroaromatic compounds, and their limits of detection (LOD) are calculated as 1.26 × 10−6 M and 1.51 × 10−6 M, respectively. The recognition mechanism for PA can be attributed to the photo-induced electron transfer (PET) process and this is supported by density functional theory (DFT) calculation. This research provides two novel compounds for the rational design of AIEE-active materials for sensing systems.

It is still a challenge to obtain two-photon excited fluorescent bioimaging probes with intense emission, high photo-stability and low cytotoxicity. In the present work, four Zn(II)-coordinated complexes (1–4) constructed from two novel D–A and D–π–A ligands (L1 and L2) are investigated both experimentally and theoretically, aiming to explore efficient two-photon probes for bioimaging. Molecular geometry optimization used for theoretical calculations is achieved using the crystallographic data. Notably, the results indicate that complexes 1 and 2 display enhanced two-photon absorption (2PA) cross sections compared to their corresponding D–A ligand (L1). Furthermore, it was found that complex 1 has the advantages of moderate 2PA cross section in the near-infrared region, longer fluorescence lifetime, higher quantum yield, good biocompatibility and enhanced two-photon excited fluorescence. Therefore, complex 1 is evaluated as a bioimaging probe for in vitro imaging of HepG2 cells, in which it is observed under a two-photon scanning microscope that complex 1 exhibits effective co-staining with endoplasmic reticulum (ER) and nuclear membrane; as well as for in vivo imaging of zebrafish larva, in which it is observed that complex 1 exhibits specificity in the intestinal system.

Highly nitrogen-doped carbon dots (N-CDs) are prepared by the pyrolysis of konjac flour under mild conditions followed with a simple extraction by ethanol and water. The N-CDs exhibit excellent pH-switched photoluminescence (PL), and their PL intensity can be facilitated by either mixing with NaOH and basic amino acids or by surface passivation with non-amine-terminated polyethylene glycols of different molecular weights. Further, the fluorescence of N-CDs can be quenched with Fe

A novel symmetrical indolo[3,2-b]carbazole derivative (ICZ-CN) containing dicyanovinyl groups has been designed and synthesized. The typical D-π-A type conjugated compound exhibited an obvious intramolecular charge transfer (ICT) property, which was evidenced by UV-vis absorption, fluorescent emission spectroscopy and density functional theory (DFT) calculations. Meanwhile, ICZ-CN exhibited a strong aggregation-enhanced emission (AEE) characteristic. Interestingly, compound ICZ-CN showed a reversible mechanofluorochromic (MFC) property between yellow and orange-red emission by grinding-fuming processes. The MFC mechanism was investigated through the single crystal structure, the scanning electron microscope (SEM) and the powder X-ray diffraction (XRD). The results showed that the mechanofluorochromic property is attributed to the loose molecular packing by weak intermolecular hydrogen bond interactions was destroyed and generated the phase transformation from crystalline to amorphous states under external stimulations. The results would be of great help in understanding and designing new MFC materials.