Search

The high incidence and difficulties of treatment of cancer have always been a challenge for mankind. Two-photon photodynamic therapy (TP-PDT) as a less invasive technique provides a new perspective for tumor treatment due to its low-energy near-infrared excitation, high targeting, and minor damage. At present, the emerging metal complexes used as the photosensitizers (PSs) in TP-PDT have aroused great interest. However, most metal complexes as PSs in TP-PDT still face some problems, such as slow clearance, unsatisfactory two-photon absorption (TPA) characteristics, high price, low reactivity, and poor solubility. In this work, density functional theory and time-dependent density functional theory were used to characterize the one/two-photon response, solvation free energy, and lipophilicity of a series of novel PSs applied in TP-PDT. The results suggest that based on complex

Profound understanding of the luminescence mechanism and structure-property relationship is vital for Cu(I) thermally activated delayed fluorescence (TADF) emitters. Herein, we theoretically simulated luminescent behavior in both solution and solid phases for two Cu(I) complexes and found the following: (i) The strengthened spin-orbit coupling (SOC) effect by more dx2-y2 orbital contributions and well-restricted structural distortion via remarkable intramolecular interaction in [Cu(dmp)(POP)]+ enable the emission at room temperature to be a mixture of direct phosphorescence (10%) and TADF (90%). (ii) Benefiting from enhanced steric hindrance and the electron-donating ability of the paracyclophane group, the narrowed S1-T1 energy separation (ΔEST) in [Cu(dmp)(phanephos)]+ accelerates the reverse intersystem crossing, promoting the TADF rate (1.88 × 105 s-1) and intensity ratio (98.3%). These results indicate that the small ΔEST is superior for reducing the lifetime and that the strong SOC stimulates the phosphorescence to compete with TADF, which are both conducive to avoiding collision-induced exciton quenching and reducing the roll-off in devices.

Investigation of the clear structure–property relationship and microscopic mechanism of thermally activated delayed fluorescence (TADF) emitters with high emission quantum yield is a direction wort...

Hypochloric acid (HOCl) plays a vital role in the natural defense system, but abnormal levels of it can cause cell damage, accelerated human aging, and various diseases. It is of great significance to develop new probes for detecting HOCl in biosystems nondestructively and noninvasively. The purpose of this work is to explore new chemical modification strategies of two-photon excitation fluorescence (TPEF) probes to improve the poor water solubility and low efficiency in imaging applications. Nil-OH-6 has a two-photon absorption cross-section value as high as 243 GM and attains a good quantum yield of 0.49. In addition, the modification of terminal groups with different azetidine-heterospirocycles or N,N-dialkyl fused amino groups to Nile Red can effectively improve the fluorescence efficiency as well as increase the solubility to some extent. This study provides some strategies to simultaneously improve the fluorescence performance and solubility of these two-photon probes and, hence, reliable guidance and a foundation for the subsequent synthesis of TPEF probes based on Nile Red.

Hypochlorous acid (HOCL) plays a critical role in the natural defense system, but excessive production of HOCL leads to many diseases. It is very essential to monitor the distribution and level of ...

Cu(I) complexes have received widespread attention as a promising alternative to traditional noble-metal complexes. Herein, we systematically study the properties of Cu(I) complexes from homo- to hetero-ligands, and found the following: (1) hetero-ligands are beneficial to regulate phosphorescent efficiency; (2) when the hetero-ligands in a tetracoordinated Cu(I) complex are 1:1, the ligands coordinate along the dx2-y2 direction of Cu(I) ion, which can observably suppress structural deformation; (3) unlike the P^P ligand, the N^N ligand can enhance the participation of Cu(I) during the transition process; (4) the addition of an appropriate amount of P^P ligand can effectively raise the energy level of HOMO (highest occupied molecular orbital), enhance the proportion of LLCT (ligand–ligand charge transfer), and thereby increase the available singlet emission transition moments which can be borrowed, thus promoting the radiative decay process. As a result, this work provides a detailed understanding of the effects of different ligands in Cu(I) complexes, and provides a valuable reference and theoretical basis for regulating and designing the phosphorescent properties of Cu(I) complexes in the future.

To develop solid-state light-emitting materials with high luminescence efficiency, determining the potential photophysics and luminescence mechanisms of the aggregation state remains a challenge and a priority. Here, we apply density functional theory to study the photophysical properties of a series of square planar Pt(II) complexes in both monomeric and dimeric forms. We reveal that four monomeric Pt(II) complexes are dominated by triplet ligand-to-ligand charge-transfer, and the lack of the triplet metal-to-ligand charge-transfer feature results in weak spin–orbit coupling (SOC), which leads to limited radiative rates; moreover, calculated nonradiative transition rates are one or two orders of magnitude higher than those radiative rates because a large amount of reorganization energy caused by the vibration of the bipyrazolate (bipz) ligand cannot be readily suppressed in the monomeric form. Therefore, four monomers exhibit photoluminescence quenching in CH2Cl2 solution in both theoretical calculations and experiments. However, in the solid state, the intense luminescence phenomenon indicates obviously distinct properties between the monomer and aggregation. We carried out a dimer model to interpret that the interaction of Pt⋯Pt induces a metal–metal-to-ligand charge-transfer excimeric state, which leads more metal components to participate in the charge transfer and enhance the SOC effect. At the same time, the ligand vibration can be significantly reduced by the shortened distance, and there is a strong π–π packing interaction in the dimer; thus, an excellent quantum yield can be achieved in aggregation. In addition, we disclose that introducing bulky substituents bearing electron-donating groups at R′ and R′′ positions have little effect on the properties of the monomers; however, there is a benefit of restricting the internal reorganization energy through the intermolecular interaction when packing in the solid state. Therefore, substitutions can be tuned to improve the properties of monomers (such as emission energy and reorganization energy). We hope that our work will shine some light on Pt(II) emitters in the fabrication of efficient OLEDs.

Profound understanding of the luminescence mechanism and structure-property relationship is vital for Cu(I) thermally activated delayed fluorescence (TADF) emitters. Herein, we theoretically simulated luminescent behavior in both solution and solid phases for two Cu(I) complexes and found the following: (i) The strengthened spin-orbit coupling (SOC) effect by more d

Investigation of the clear structure-property relationship and microscopic mechanism of thermally activated delayed fluorescence (TADF) emitters with high emission quantum yield is a direction worthy of continuous efforts. The instructive theoretical principle of TADF material design is critical and challenging. Here, we carried out theoretical calculation on two experimental Cu(I) complexes with the same 7,8-bis(diphenylphosphino)-7,8-dicarba

Correction for ‘New insight into the effects of N^N ligand isomerization and methyl modification on the phosphorescence properties of Cu(i) complexes with (1-(2-pyridyl)pyrazole/imidazole) ligands’ by Lu Shen et al., New J. Chem., 2018, 42, 3660–3670, https://doi.org/10.1039/C7NJ04879C.

In this paper, we conducted DFT and TDDFT calculations on three double heteroleptic Cu(I) complexes to understand how different substituents on N^N ligands influence the phosphorescence quantum yield (PLQY). Both radiative and nonradiative decay processes were thoroughly investigated. Factors that determine the rate of radiative process (kr) were considered, including the lowest triplet excited state E(T1), the transition dipole moment MSm,j of the Sm → S0 transition, the spin-coupled matrix element SOC, and the singlet–triplet splitting energies ΔE(Sm–T1). The results indicate that E(T1), MSm,j and SOC increase and ΔE(Sm–T1) decreases upon introducing –Ph and –CH2– groups on the N^N ligands. The net results lead to a gradual increase of kr in the three Cu(I) complexes, from 1 (0.48 × 104 s−1) to 2 (0.64 × 104 s−1) and then to 3 (1.61 × 104 s−1). The rate of nonradiative decay process (knr) was computed by a convolution method. We explored how knr is determined by SOC between T1 and S0 states (〈T1|SOC|S0〉2), effective energy gap ΔE′ and the Huang–Rhys factor (S). We found that 〈T1|SOC|S0〉2 and ΔE′ contribute significantly to knr, but S does not determine the order of knr. knr gradually decreases from complex 1 (2.51 × 106 s−1) to 2 (0.32 × 106 s−1) and then to 3 (0.14 × 106 s−1) after introducing –Ph and –CH2– groups on the N^N ligands. The computed PLQYs for the three complexes are 1: 0.0019, 2: 0.0198, and 3: 0.1011. These are quantitatively consistent with the experimental observation (1: 0.0028, 2: 0.0061, and 3: 0.1000).

Various tetrahedral heteroleptic Cu(I) complexes, as red organic light-emitting diodes (OLEDs), show a concern of maximizing the quantum yield (QY) in order to improve the optoelectronic performance. Herein, three experimental [Cu(N^N) (bis [2-(diphenylphosphino)phenyl]ether)]+ (named 1, 2 and 3) were selected as the jumping-off point, following two complexes (named 4 and 5) were successfully designed by introducing bulky electron-donating substituents into N^N ligands continuously. As expected, the QY of designed complexes 4 (0.26) and 5 (0.13) exhibit over twice higher than that of 3 (5.4 × 10−2). This can be attributed to the enhanced electron-donating property of N^N ligand, which accelerated the radiative transition rate (kr) through the apparently elevated energy level of the lowest triplet excited state (T1) and strengthened transition dipole moments, even though the spin-orbit coupling (SOC) effect is weakened. Simultaneously, the tetrahedral geometric distortion could be effectively restrained by the bulky N^N ligands, but the high vibrational freedom of the terminal substituents could also bring in some unfavorable intra-ligand deformation, resulting in an upward of the nonradiative transition rate (knr) at 5 (knr: 0.30 × 105 s−1 for 4; 0.95 × 105 s−1 for 5). Therefore, it's worth noting that the balance of excited state energy level, SOC effect as well as the reorganization energy ought to be elaborately regulated to achieve the optimal QY. This detailed investigation on the microscopic mechanism of these Cu(I) complexes can provide instructive inspiration for experimentalists.

The evaluation methods for asphalt pavement preventive maintenance both local and abroad are investigated in this study. A comprehensive evaluation model that combines the evaluation index of pavement and material performance in domestic technical specifications and that considers the lack of weight allocation method for evaluation indices is proposed for the preventive maintenance of asphalt pavement. On the basis of the combination of practical engineering experiences, the expert scoring method, and experimental testing data, the model utilizes a new method, i.e., the improved entropy weight-analytic hierarchy process, to calculate the comprehensive weight coefficients of various evaluation indices and to evaluate the effect of preventive maintenance. The preventive maintenance engineering of highway asphalt pavement in Zhangjiakou is used as an example. Results show that the model is feasible. Moreover, the results can provide technical support for the application of preventive maintenance measures to asphalt pavement.

We herein report a theoretical study using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to investigate Cu(I) complexes with 2-(2′-pyridyl/quinolyl)imidazole and bis[2-(diphenylphosphino)phenyl]ether mixed ligands. Based on the experimental data for complexes 1 and 2, we first benchmarked different functionals with different HF% and found B3PW91 to be the optimal functional for this system. The computational results indicate that complex 1, with a pyridyl unit, has a much larger radiative decay rate (kr) than complex 2, which has a quinolyl unit. This difference is presumably due to higher HOMO electronic distribution in the dx2-y2 orbital, which leads to a markedly shortened Cu N2 bond, enhancing the metal-ligand interaction. However, a much smaller experimental value was found for the non-radiative decay rate (knr) in complex 2, rendering 1 a slightly weaker emitter than 2. We conclude that the difference is due to more effective suppression of deformation when the quinolyl unit is used instead of pyridyl. We sought to increase the photoluminescence quantum yield (PLQY) through modifying the ligand on complex 2, with the goal being to keep the small knr value while simultaneously increasing kr. The computational results indicate that our designed complexes 2a-2c, which possess modified ligands with electron-donating or withdrawing alkyl substituents on N3, increased the distributions of dx2-y2 and decreased that of the dyz compared to 2. Their coordinating abilities were therefore enhanced, with the kr values being 1.34, 22.70, and 0.16 times that of 2 for 2a, 2b and 2c, respectively. Higher PLQYs were achieved in 2a and 2b with the addition of electron-donating alkyl substituents on the ligands, which yielded complexes with significantly shortened Cu N2 bonds and enhanced metal-ligand interaction. This investigation on the microscopic mechanism of the photoluminescent properties of these complexes can provide useful knowledge for experimentalists.

MicroRNA390 (miR390), an ancient and highly conserved miRNA family in land plants, plays multiple roles in plant growth, development and stress responses. In this study, we isolated and identified MIR390, miR390, TAS3a/b/c, tasiARF-1/2/3 ( t rans- a cting s mall i nterfering RNAs i nfluencing A uxin R esponse F actors) and ARF2/3/4 in Jerusalem artichoke (Helianthus tuberosus L.). Treatment with 100 mM NaCl induced expression of miR390, increased cleavage of TAS3, produced high levels of tasiARFs, and subsequently enhanced cleavage of ARF3/4, which was most likely associated with salt tolerance of the plants. In contrast, treatment with 300 mM NaCl inhibited expression of miR390, attenuated cleavage of TAS3, produced a small amount of tasiARFs, and reduced cleavage of ARF3/4. We proposed that ARF2, one of the targets of tasiARFs, induced under salinity was likely to play an active role in salt tolerance of Jerusalem artichoke. The study of the miR390-TAS3-ARF model in Jerusalem artichoke may broaden our understanding of salt tolerance mechanisms, and provides a theoretical support for further genetic identification and breeding crops with increased tolerance to salt stress.

Cysteine is an essential amino acid in the synthesis of human protein. Therefore, the effective detection of cysteine in living organisms is of great significance. In this paper, first-principles are used to systematically study the fluorescence recognition mechanism and two-photon absorption properties of a series of novel two-photon (TP) fluorescent probes for cysteine. These probes are constructed based on coumarinocoumarin derivatives possessing the excellent fluorescence properties of coumarin molecules and the experimental fact that sporadic coumarinocoumarin can be used as a fluorescent probe, the recognition of which depends on enabled photo-induced electron transfer (PET) and intramolecular charge transfer (ICT) mechanisms toward cysteine. The results show that the transition dipole moments of coumarinocoumarin and monomer coumarin are significantly different, which allows the coumarinocoumarin to break the limit of the linear increase in the dipole moment vector of the monomer coumarin in the direction and magnitude. The magnitude of the two-photon cross-section value ( δ max T ) depends on the state dipole moment ( μ j j ( μ i i )) of the transition channel and the transition dipole moment ( μ i j ) of the coherent channel. Through the above research, we propose that (1) the length of the π conjugated chain can be increased along the 7-site of the coumarinocoumarin skeleton; (2) extend the π conjugated chain along different paths to change the state dipole moment of the transition channel of the target molecule and the direction of the transition dipole moment vector of the coherent channel to improve the TPA cross-section values of the probe molecule. Moreover, maximum TPA can be achieved in the range of 700–1000 nm for designed probe molecules, effectively avoiding factors such as the self-fluorescence of biological tissues and background interference. CCy-1-OH ∼ CCy-3-OH and CCy-7-OH molecules are designed to be excellent candidates for TP fluorescent probes. We hope the study can provide useful theoretical basis for cysteine imaging research.

Heterocyclic ligands based on 2-pyridyl-azole, have become some of the ideal ligands for metal complexes due to their flexible structure and wide wavelength tunability. In this paper, a series of Cu(N∧N) (P∧P) complexes are studied by density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The results indicate that the combination of incorporation of N atoms and substitution of electron donor-acceptor groups can effectively control the type and the proportion of the lowest triplet states (T1) phosphorescent transition. A higher matching degree between the effective spin-orbit coupling (SOC) matrix elements and the transition dipole moments (The Sn state has both effective SOC and large transition dipole moments of Sn→S0 transition) brings about a larger transition dipole moment MTa of T1a→S0 transition, and further results in the fastest radiative decay rate (kr) for complex 2, although the main transition of which is internal-ligand charge transfer (ILCT). In addition, the non-radiative decay rate (knr) of complex 2 is lower than other complexes of series 3 (the reorganization energy produced by in-plane bending vibration of C–H bond in six-membered ring is larger than complex 2), so this complex has the highest quantum yield. Overall, the above analyses illustrate that despite the participation of Cu(I) in transition as an indispensable factor for the radiative transition, the higher component ratio does not necessarily lead to a faster kr. In addition, it is also essential to have a well-matched large transition dipole moments of the singlet states Sn→S0 transition involved in the effective SOC. Consequently, in the development of the 2-pyridyl-azole Cu(I) luminescent materials, the high quantum yield materials can be designed by adjusting the substituent at C3 position and the strength of electron donor-acceptor groups at C5 position to balance the charge transfer transition modes.

This paper, through the analysis of the serious problems of jiao River such as the deterioration of water environment and water pollution, puts forwards the water protection measures, on the basis of which we appeal to the governments at all levels to attach great importance to jiao River pollution management and actively improve jiao River water environment. At the same time, the paper hopes all of our citizens could contribute to the improvement of jiao River environment.

this paper analyses the reutilization of waste concrete is feasible in technology, technical index, and its concrete recycling huge economic, environmental benefits.

Now concrete beams reinforced with near surface mounted FRP bars has been researched at home and abroad. This article research the Bearing capacity of concrete beams reinforced with near surface mounted FRP bars by test, and also, Immunobead binding test, infer the calculation formula of ultimate bearing capacity with near surface mounted some bars base on the the single bar.

Forest fires are harmful to the ecological environment, which have induced global attention. In the present paper fire activities extracted from MODIS and burned areas were compared, and it was found that the wave band of 8-9 extracted from MOD14A1 was useful for fire monitoring, and the data accorded with field investigation with goodness of fit reaching up to 0. 83. Through combining this wave band and the relative data to make the time and space analysis of the forest fires for 11 years, from 2000 to 2010, the study showed that the fire occurred most frequently in the spring, the autumn took the second place, and in the summer there was almost no fire occurrence unless drought. Through the analysis of the research area, the burned areas of the coniferous forest and temperate mixed forest were 53.68% and 44%, respectively, while the grassland was only 2.32%. Da Hinggan Ling region was the main combustion area, the burned areas were 64.7% and that for Xiao Hinggan Ling was about 23.49%, while those for other areas were less than 5%. The majority of forest land of burned areas has a gentle slope (or =5 percent), and is in the middle altitude between 200 and 500 m. So, using satellite remote sensing to analyze the time series of burned areas in forests would make the relationship between the fire activities, climate change, topography and vegetation type clear and it is also helpful to predicting the risk level of the fire areas.

To investigate the correlation of single nucleotide polymorphisms (SNP) of XRCC1 gene to hereditary susceptibility of colorectal cancer.XRCC1 genotypes in 124 colorectal cancer patients and 214 matched healthy people as control were analyzed by SnaP Shot SNP-typing technique. Five different inheritance models including codominant, dominant, recessive, overdominant and log-additive were analyzed using logistic regression model. The haplotype distribution was estimated with phase and its correlation with the risk of colorectal cancer was evaluated.The frequencies of mutant 25487G-A, 25489C-T and 1799782C-T alleles were 0.20, 0.11, 0.32 respectively in the patients, and 0.23, 0.13, 0.34 in the controls. There was no significant correlation of polymophisms of XRCC1 gene to the risk of colorectal cancer in 5 different inheritance models (P0.05). GCT, GCC, ACC and GTC were the most common haplotypes and the odds ratios were 1, 1.35, 0.90 and 0.84 respectively. There was no significant difference of distribution between 2 groups in haplotypes.Polymorphisms of XRCC1 gene, including rs25487, rs25489, rs1799782, are not associated with to the risk of colorectal cancer.

To compare proximal gastrectomy (PG) with total gastrectomy (TG) for proximal gastric carcinoma, through the 5-year survival rate, recurrence rate, postoperative complications, and long-term life quality.The meta-analysis was carried out in the General Surgery Department of the Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China. We searched Medline, EMBASE, and the Cochrane Library from June to November 2012. The literature searches were carried out using medical subject headings and free-text word: `proximal gastrectomy` `total gastrectomy` `partial gastrectomy` `stomach neoplasms` and `gastric cancer`. Two different reviewers carried out the search and evaluated studies independently.Two randomized controlled trials and 9 retrospective studies were included. A total of 1364 patients were included in our study. Our analysis showed that there is no statistically significant difference in 5-year survival rate between PG and TG (60.9% versus 64.4%). But, the recurrence is higher in the PG group than the TG (38.7% versus 24.4%). The anastomotic stenosis rate is also higher in the PG than the TG (27.4% versus 7.4%).Proximal gastrectomy is an option for upper third gastric cancer in terms of safety. However, it is associated with high risk of reflux symptoms and anastomotic stenosis. Therefore, TG should be the first choice for proximal gastric cancer to prevent reflux symptoms.

The transcriptional activity of the SARP19-I1 and vdg3-I1 genes increases over tenfold when Haliotis diversicolor larvae shift from the pelagic to benthic lifestyle, signifying the important role of these genes during abalone metamorphosis. In this study, eight paralogous SARP19 genes and six paralogous vdg3 genes were identified from H. diversicolor transcriptomes. Phylogenetic analyses were performed, and the spatio-temporal expression patterns of these genes were separately determined by quantitative polymerase chain reaction (qPCR) and whole mount in situ hybridization (WMISH). Five SARP19 paralogs and five vdg3 paralogs showed at least a tenfold increase in expression after settlement. Among these differentially expressed genes, three SARP19 paralogs and four vdg3 paralogs were verified as being spatially expressed in the digestive glands of newly settled postlarvae. We proposed that a hypothesis of coevolution between the two gene families might explain the similarities in their expression patterns and their phylogenetics.