Molecular Extinction Coefficient Research Articles

In-silico analysis of ribosome inactivating protein (RIP) of the Cucurbitaceae family.

Ribosome-inactivating proteins (RIPs) are highly active N-glycosidases that depurinate both bacterial and eukaryotic rRNAs, halting protein synthesis during translation. Found in a diverse spectrum of plant species and tissues, RIPs possess antifungal, antibacterial, antiviral, and insecticidal properties linked to plant defense. In this study, we investigated the physiochemical properties of RIP peptides from the Cucurbitaceae family through bioinformatics approaches. Molecular weight, isoelectric point, aliphatic index, extinction coefficient, and secondary structures were analyzed, revealing their hydrophobic nature. The novelty of this work lies in the comprehensive examination of RIPs from the Cucurbitaceae family and their potential therapeutic applications. The study also elucidated the binding interactions of Cucurbitaceae RIPs with key biological targets, including Interleukin-6 (IL-6). Strong hydrogen bond interactions between RIPs and these targets suggest potential for innovative insilico drug design and therapeutic applications, particularly in cancer treatment. Comprehensive analysis of bond lengths using Ligpolt + software provides insights for optimizing molecular interactions, offering a valuable tool for drug design and structural biology studies.

HSA-ZW800-PEG for Enhanced Optophysical Stability and Tumor Targeting.

Small molecule fluorophores often face challenges such as short blood half-life, limited physicochemical and optical stability, and poor pharmacokinetics. To overcome these limitations, we conjugated the zwitterionic near-infrared fluorophore ZW800-PEG to human serum albumin (HSA), creating HSA-ZW800-PEG. This conjugation notably improves chemical, physical, and optical stability under physiological conditions, addressing issues commonly encountered with small molecules in biological applications. Additionally, the high molecular weight and extinction coefficient of HSA-ZW800-PEG enhances biodistribution and tumor targeting through the enhanced permeability and retention effect. The unique distribution and elimination dynamics, along with the significantly extended blood half-life of HSA-ZW800-PEG, contribute to improved tumor targetability in both subcutaneous and orthotopic xenograft tumor-bearing animal models. This modification not only influences the pharmacokinetic profile, affecting retention time and clearance patterns, but also enhances bioavailability for targeting tissues. Our study guides further development and optimization of targeted imaging agents and drug-delivery systems.

Detection of Atmospheric Wind Speed by Lidar Based on Quadrichannel Mach–Zehnder Interferometer

For a long time, wind speed profile measurement has been the primary task of weather forecasting. Therefore, the detection of atmospheric wind speed is extremely important for studying the changes in atmospheric motion. In order to solve the problems of insufficient data collection, low resolution, and low accuracy in atmospheric wind field detection, this paper introduces the relevant theories of wind speed detection, completes the optical design of the system according to the research objectives, and determines the selection of optical devices. At the same time, a Doppler wind lidar system based on a quadrichannel Mach–Zehnder interferometer is designed and built to carry out ground-based observation experiments, collect echo signal data, and inverse the atmospheric radial wind speed. Furthermore, the wind measurement error is analyzed. Firstly, the paper introduces the basic principle of the wind measurement system, i.e., using the Doppler effect of light, and then analyzes the frequency discrimination device of the system in detail, and obtains the theoretical calculation method of atmospheric wind speed inversion. At the same time, the relevant datasets of wind measurement system are analyzed, including backscattering ratio, aerosol, and molecular extinction coefficient, and the emission mechanism of the large pulse laser is also studied in detail, which provides a theoretical basis for the model construction of Doppler lidar and the research on the enhancement of pulsed laser emission energy. Secondly, according to the research index of wind measurement, a Doppler wind measurement lidar system based on a quadrichannel Mach–Zehnder interferometer is designed, including the design of ab external light path transceiver system, internal light path interferometer, software and hardware, and algorithm. The calibration of the quadrichannel Mach–Zehnder interferometer is completed, with its maximum interference contrast reaching 0.869. Through the self-developed optical transceiver system and data acquisition system, the echo signal of lidar is received and detected. Lastly, the data of echo signals collected by the interferometer are analyzed, the radial atmospheric wind speed profile is inversed, and the signal-to-noise ratio and wind speed measurement error of the system are evaluated. The experimental results show that the maximum signal-to-noise ratio (SNR) of the system can reach 1433 when the emission pulse energy of the large pulse laser is adjusted to 255 mJ, and the farthest wind speed detection distance is about 8 km. The high-precision wind speed detection range can reach 2 km, the actual wind measurement errors in this range are all within 1.593 m/s, and the minimum error is only 0.418 m/s. In addition, the backscattering coefficient and extinction coefficient of atmospheric molecules and aerosols in the range of 8 km and the atmospheric temperature in the range of 10 km are also measured. The measurement accuracy of the aerosol extinction coefficient is ±0.001 m−1, and the measurement error of atmospheric temperature within 10 km is within 2 K, achieving the expected goals.

Impact of charge character on anionic cyanine-based organic salt photovoltaics

Small bandgap organic compounds with absorption in the near-infrared are exciting materials for a variety of applications ranging from light harvesters in photovoltaics to active agents in photodynamic therapy. Organic salts, a class of small molecule organic compounds comprised of an ionic chromophore and a counterion, have been used in opaque and transparent photovoltaics, primarily as donor materials in bilayer architectures. They possess excellent molecular extinction coefficients with near-infrared selective absorption, adjustable bandgaps, and tunable energy levels. To approach organic salt photovoltaics from a new perspective, we fabricated devices with an unexplored group of anionic salts comprised of a near-infrared absorbing chromophore paired with a varying number of cationic counterions. We observed different donor and acceptor decay trends in external quantum efficiencies that allowed us to separate and independently quantify exciton diffusion and charge transfer for each salt. Increased charge character on the chromophore greatly improves hole transport, as anions with a net −3 charge have charge collection lengths greater than four times those of corresponding singly charged chromophores. This presents an interesting platform for independent quantification of exciton diffusion and charge transport of an active material in a single photovoltaic device and demonstration of the important role of charge on the chromophore. The dependence of charge transport capabilities on charge character of the chromophore will be a useful tool in the design of future organic salts to engineer materials for higher efficiency transparent photovoltaics.

Cooperation of σ-π and σ*-π* Conjugation in the UV/Vis and Fluorescence Spectra of 9,10-Disilylanthracene.

In 1996, we reported that silyl groups of 9,10-disilylanthracenes significantly affect the UV/Vis and fluorescence spectra. Although the results indicate that the silyl groups have strong electronic effects on anthracene, the details of the mechanisms responsible for this have not yet been clarified. This article describes the analysis of the UV/Vis and fluorescence spectra of 9,10-bis(diisopropylsilyl)anthracene by theoretical calculations. This study reveals that π conjugation of anthracene is extended by cooperation of σ–π and σ*–π* conjugation between the silyl groups and anthracene. This effect increases the transition moment of the π–π* transition of anthracene. As a result, the molecular extinction coefficient of the 1La band and the fluorescence quantum yield are increased.

IMPACT OF CHLORPYRIFOS ON BACILLUS CEREUS OP3 SOIL BACTERIA ISOLATED FROM RHIZOSPHERE

Chlorpyrifos is a pesticide belongs to organophosphate group and widely used in Indian agriculture. The evaluation of chlorpyrifos removal from the soil using pesticide degrading bacteria will help in the resilience of soil fertility. Bacteria capable of degrading chlorpyrifos were isolated from chlorpyrifos-treated agricultural soil. The degradation of chlorpyrifos by a potential isolate was determined using FTIR and quantified using the molecular extinction coefficient in an ELISA reader. GC-MS was used to analyze the chlorpyrifos degradation metabolites. Additionally, the effect of chlorpyrifos exposure on genomic DNA and total protein content was determined. A total of 174 bacterial colonies were isolated, of which only 40 bacterial colonies were pesticide tolerant in 100ppm chlorpyrifos. Among them, only three isolates (OP3, OP5, and OP7) demonstrated tolerance above 100ppm. Within five days of incubation, OP3 demonstrated tolerance to chlorpyrifos concentrations up to 300ppm and 47 percent of chlorpyrifos was removed. By 16S rRNA sequencing, potential OP3 isolates were identified as Bacillus cereus OP3. FTIR spectra confirmed that B. cereus degraded chlorpyrifos, with 92.4 percent of chlorpyrifos degraded. In GC-MS analysis, metabolites such as MNitroaniline and 4-Methyl-2-{(4-Nitrophenyl)Thio}Pyrimidine were detected. Chlorpyrifos overexposure alters the total protein content of exposed cells and induces DNA breaks. As a result, it is concluded that B. cereus is able to degrade chlorpyrifos and the excessive use of pesticides make some changes in the soil bacteria. Overexposure of chlorpyrifos leads to an increase in total protein content and induce DNA strands breaks in pesticide degrading Bacillus cereus.

Performance of asymmetric non-fullerene acceptors containing the 4,4,9,9-tetramethyl-4,9-dihydroselenopheno[2',3':5,6]-s-indaceno[1,2-b]thiophene core

Through changing the terminated groups, three asymmetric non-fullerene acceptors containing a 4,4,9,9-tetramethyl-4,9-dihydroselenopheno[2',3':5,6]-s-indaceno[1,2-b]thiophene fused-ring core were designed and synthesized. The resultant acceptor-donor-acceptor (A-D-A) type of small molecules all show broad absorption spectra with tunable molecular energy levels and distinct molar extinction coefficients in solutions. The 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile terminated molecule (T-Se), has the smallest molar extinction coefficient of 1.83 × 105 M−1cm−1 with a bandgap of 1.62 eV, and a high-lying lowest unoccupied molecular orbital (LUMO) energy level (−3.83 eV). For the fluorinated molecule T-Se-4F, its molar absorption coefficient is enhanced to 2.05 × 105 M−1 cm−1, and its bandgap is narrowed to 1.58 eV, while its LUMO energy level is down-shifted to −3.93 eV. As for the molecule T-Se-Th having thiophene functionalized end-group, although the acquired LUMO energy level (−3.88 eV) is in between that of T-Se and T-Se-4F, it possesses the largest molar extinction coefficient (2.40 × 105 M−1cm−1), and a moderate bandgap of 1.60 eV. In solar cells with PM6 as electron-donor, the T-Se-4F- and T-Se-Th-based devices have superior exciton dissociation and charge collection properties, more weakly bimolecular recombination probabilities, and better electron transportability. As the results of the preceding characteristics, the T-Se-4F- and T-Se-Th-based devices achieve a higher current of 18.09 and 16.90 mA cm−2, better fill factors of 66.6 and 66.8%, relative to the 12.80 mA cm−2 and 62.1% of the T-Se-based device. Benefitting from the medium open-circuit voltage (VOC, 0.912 V), the T-Se-Th-based device successfully achieved the best power conversion efficiency of 10.29% among the three molecules. In contrast, the T-Se- and T-Se-4F-based devices owned the highest VOC of 0.935 V and the lowest VOC of 0.781 V, leading to the low efficiency of 7.44% and moderate efficiency of 9.41%, respectively, revealing the significant impact of the terminal groups on the properties of 4,4,9,9-tetramethyl-4,9-dihydroselenopheno[2',3':5,6]-s-indaceno[1,2-b]thiophene based asymmetric non-fullerene acceptors.

Accepting to Donate: NDI‐Based Small Molecule as a Donor for Bulk Heterojunction Binary Solar Cells

A small molecular D‐π‐A‐π‐D triad NDIP consisting of naphthalenediimide (NDI) as an acceptor and porphyrin as a donor was synthesized. NDIP exhibits an intense absorption from visible to NIR region (400 nm to 1000 nm) with high molecular extinction coefficient. Endowed with excellent absorption and good charge carrier mobility, the molecule was used as a donor, against the normal perception as an acceptor due to the electron‐deficient nature of NDI, in the binary bulk heterojunction solar cells with PCBM as an acceptor. The cell demonstrated remarkable power conversion efficiency of 8.45 % with extremely low Eloss of 0.40 eV, which is also the best recorded for NDI based small molecule organic solar cells.

Thermodynamic Study and Spectroscopic Analysis of a Charge-Transfer Complex between 3,5-Diamino-1,2,4-Triazole and 6-Methyl-1,3,5-Triazine-2,4-Diamine with Chloranilic Acid

Studying of charge-transfer (CT) and proton transfer interactions is essential due to their important role in many biological field and industrial applications. The current work will add more information’s about the nature of interaction between 3,5-diamino-1,2,4-triazole (DAT) and 6-methyl-1,3,5-triazine-2,4-diamine (MTDA) with 3,6-dichloro-2,5-dihydroxy-p-benzoquinone (chloranilic acid CLA) which was studied spectrophotometrically in Ethanol (EtOH) and Methanol (MeOH) solvents at different temperatures. The molecular composition of the formed complexes was studied by applying continuous variation and spectrophotometric titration methods and found to be 1:1 charge transfer complex for both Complex (DAT:CLA) and (MTDA:CLA) which are produced. Minimum-Maximum absorbance’s method has been applied to calculate the formation constant KCT and molecular extinction coefficient (ε); they recorded high values confirming high stability of the produced complexes. Oscillator strength (f), transition dipole moment (μ), ionization potential (IP) and dissociation energy (W) of the formed CT-complexes were also determined and evaluated; they showed solvent dependency. It is concluded that the formation constant (KCT) of the complexes is found to depend on the nature of both electron acceptor and donors and on the polarity of solvents.

Synthesis, Characterization, and Biological Evaluation of a New Hydrogen-Bonded Charge-Transfer Complex of 2-Amino-4-methoxy-6-methylpyrimidine

A new hydrogen-bonded charge-transfer (HB-CT) complex formed between the donor 2-amino-4-methoxy-6-methylpyrimidine (AMMP) and theπ-acceptor 2,5-dihydroxy-p-benzoquinone (DHBQ) was investigated in both solid and solution states. The investigation was conducted using UV-Vis, CHN, FTIR,1H NMR, XRD, and TG-DTA analyses. The molecular composition of the CT complex in MeOH was found to be 1 : 1. The formation constant (KCT), molecular extinction coefficient (ε), and several other spectroscopic physical parameters were evaluated at different temperatures. The thermodynamic properties of the CT interaction in MeOH were studied by calculating the enthalpy (ΔH°), entropy (ΔS°), and free energy (ΔG°). The thermodynamic parameters indicated that van der Waals interactions and hydrogen bonding occur between AMMP and DHBQ in MeOH. The CHN, FTIR, and TG-DTA measurements confirmed that the solid HB-CT complex forms in a 2 : 1 ratio, i.e., [(AMMP)2(DHBQ)], and exhibits high stability. Moreover, XRD analysis was used to establish that the mean particle size of the complex is 23 nm. Finally, the solid HB-CT complex was screened for its antibacterial, antifungal, and antioxidant activities. It shows good activity against various bacterial and fungal species. Furthermore, the HB-CT complex exhibits good DPPH scavenging activity.

Using Chou's General Pseudo Amino Acid Composition to Classify Laccases from Bacterial and Fungal Sources via Chou's Five-Step Rule.

Laccases are a group of enzymes with a critical activity in the degradation process of both phenolic and non-phenolic compounds. These enzymes present in a diverse array of species, including fungi and bacteria. Since this enzyme is in the market for different usages from industry to medicine, having a better knowledge of its structures and properties from diverse sources will be useful to select the most appropriate candidate for different purposes. In the current study, sequence- and structure-based characteristics of these enzymes from fungi and bacteria, including pseudo amino acid composition (PseAAC), physicochemical characteristics, and their secondary structures, are being compared and classified. Autodock 4 software was used for docking analysis between these laccases and some phenolic and non-phenolic compounds. The results indicated that features including molecular weight, aliphatic, extinction coefficient, and random coil percentage of these protein groups present high degrees of diversity in most cases. Categorization of these enzymes by the notion of PseAAC, showed over 96% accuracy. The binding free energy between fungal laccases and their substrates showed to be considerably higher than those of bacterial ones. According to the outcomes of the current study, data mining methods by using different machine learning algorithms, especially neural networks, could provide valuable information for a fair comparison between fungal and bacterial laccases. These results also suggested an association between efficacy and physicochemical features of laccase enzymes from different sources.

Development of an environmentally-friendly solvent-free extraction of saffron bioactives using subcritical water

Subcritical water extraction (SWE) of saffron major bioactive compounds – picrocrocin, safranal and crocin– was conducted. The influence of extraction time (5–15 min) and temperature (105–125 °C) on the process efficiency was investigated through response surface methodology (RSM). The components were determined through spectrophotometry at 257, 330 and 440 nm, namely the wavelengths at which picrocrocin, safranal and crocin have the highest absorbance respectively. The molecular extinction coefficient(E1cm%1λmax) was measured for each component at its corresponding wavelength. Our results revealed that moderate extraction times and low temperatures had the best impact on the yields of picrocrocin and safranal indicating the partial thermal stability of these two compounds. The crocin content decreased dramatically by increasing time and temperature revealing the sensitivity of this component to subcritical conditions. Extraction temperature of 105 °C and time of 7.32 min were acquired as the optimum conditions which delivered E1cm%1λmax of 88.262, 45.482 and 145.26 for picrocrocin, safranal and crocin, respectively. HPLC analysis demonstrated that SWE process degraded most of saffron crocins. GC-MS identified only safranal with a retention time of 6.752 min and a molecular weight of 150.

Visible-to-Near-Infrared Light-Driven Photocatalytic Hydrogen Production Using Dibenzo-BODIPY and Phenothiazine Conjugate as Organic Photosensitizer

A novel visible-to-near-infrared (visible-to-NIR) light-driven photocatalyst was prepared by loading a dibenzo-BODIPY-phenothiazine conjugate dye 1 as a panchromatic photosensitizer on hierarchical porous TiO2 (HPT) semiconductor. The sensitizer 1, which absorbed visible light at 638 and 440 nm with molecular extinction coefficients (e) of 1.23 × 105 and 1.80 × 104 M–1 cm–1, respectively, in THF due to the dibenzo-BODIPY and phenothiazine-based D−π–A systems, respectively, showed panchromatic absorption up to 780 nm when deposited on the Pt/HPT photocatalyst to produce Pt/HPT500/1. The photocatalytic activities were investigated in the presence of ascorbic acid as a sacrificial agent in phosphate buffer solution under irradiation with λ > 400 nm using a 300 W Xe lamp at 100 mW cm–2 light intensity. After 10-h irradiation, the system achieved a remarkable catalytic activity for the production of H2 with a turnover number (TON) value of 11100. The sustained activity was suggestive after two sequences of 10-...

Spectrophotometric, Thermodynamic and Density Functional Studies of Charge Transfer Complex Between Benzhydryl Piperazine and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone

The charge transfer complex of benzhydryl piperazine as donor with the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinone has been studied spectrophotometrically in acetonitrile medium at different temperatures. On mixing the donor with acceptor, a reddish brown colored charge transfer complex is formed. Electronic absorption spectra of the complex show charge transfer bands at 587, 546 and 457 nm. The molecular composition of the complex was studied by applying Job’s continuous variation and spectrophotometric titration methods. These results support the formation of the complex in a 1:2 ratio. The Benesi–Hildebrand equation has been applied to compute the formation constant and molecular extinction coefficient. Thermodynamic parameters of the charge transfer complexation reaction (standard entropy, standard enthalpy and standard Gibbs free energy) have been calculated. The results of the spectrophotometric study demonstrated that the charge transfer complex formation is endothermic. The computational studies of the charge transfer complex were performed by using the Gaussian 09 W package of programs. The bond lengths, bond angles, dihedral angles, Mulliken atomic charges, molecular electrostatic potential maps and characterization of the highest occupied molecular orbital and lowest unoccupied molecular orbital surfaces of charge transfer complex were computed.

Synthesis and characterization of novel bis-(4-methylcoumarin) derivatives as photosensitizers in antimicrobial photodynamic therapy

Abstract Four coumarin derivatives were synthesized via the reaction of coumarin by four compounds namely 1,3-dibromopropane, 1,3-bis(bromomethyl)benzene, 1,4-bis(bromomethyl)benzene, and 2,6-bis(bromomethyl)naphthalene. The chemical structures of the prepared compounds were characterized by FTIR, 1H NMR and mass spectroscopy. The photophysical properties of the prepared compounds were determined by measuring the absorption and emission spectra. The photophysical properties of the prepared compounds were calculated such as: (e) molecular extinction coefficient; (σa) absorption cross section, (φf) fluorescence quantum yield, (τo) fluorescence life time, (f) oscillator strength, (Kisc) the intersystem crossing rate, (Kr) the radiative decay rate. The prepared compounds exhibited UV–vis absorption spectra in the absorption region of 250–350 nm with a maximum absorption peak at of 321 nm, and emission spectra were obtained in the range of 340–440 nm with different intensities depending on their chemical structures. In vitro microbiological investigation of the prepared coumarin derivatives in dark and UV irradiation was performed. All the compounds exhibited biocidal activities. Antimicrobial assay of the prepared compounds in dark showed their potency against the tested microorganisms. The antimicrobial assay in the presence of UV irradiation showed the photodynamic therapeutic activities of the coumarin derivatives. The photodynamic therapeutic activities were correlated to the photophysical properties of the tested compounds and their interaction by the cellular membranes.

Influence of a local electric field on the light harvesting efficiency of a cyclopentadithiophene-bridged D-A-π-A indoline dye on pure and N-doped TiO2 surfaces

The primary objective of this paper is to study the influence of the local electric field at the dye/semiconductor (pure and nitrogen doped TiO2) interface on the performance of dye sensitized solar cells (DSSCs). In this regard, as a first step, we explored the influence of electric field on the performance of the WS-51 dye by computing its properties in an electric field up to 15 × 10−4 a.u. The electronic and optical properties of an established, efficient, donor-acceptor-π-acceptor dye in different electric field strengths were probed with density functional theory (DFT) and time-dependent DFT. The calculated results indicate that, under an electric field, the dye shows significant changes in absorption spectrum due to considerable changes in molecular structure. The TD-DFT results indicate that the absorption spectrum of the dye in acetonitrile solution have shown a blue shift with decreasing molecular extinction coefficient by rising electric field strength. Secondly, we investigated the dye adsorbed on Ti48O96 and Ti48O95N clusters. In the applied field off state, the absorption spectrum of the dye/Ti48O95N system is red shifted with an improved molecular extinction coefficient as compared to the dye/Ti48O96 system, indicating that the nitrogen doped TiO2 surface is more favourable for enhancing the efficiency of the DSSCs. Finally, the calculated results suggested that the light harvesting efficiency (LHE) of the dye/Ti48O95N system is higher than that of the dye/Ti48O96 system. But, under an electric field the LHE of the dye on Ti48O96 and Ti48O95N clusters is likely to decrease with increasing electric field strength. The photon to current response of the DSSCs is limited by the local electric field generated at the dye – semiconductor interface. Finally, results indicate that the doping of a nitrogen atom in TiO2 moderates the electric field intensity at the dye – semiconductor interface. Therefore, the results obtained in this study will provide a valuable reference for understanding the role of local electric field for the further optimization of DSSCs.

Analysis and comparison of lignin peroxidases between fungi and bacteria using three different modes of Chou’s general pseudo amino acid composition

Lignin peroxidases (LiPs) are important enzymes in the degradation process of lignin which are presented in different species of fungi and bacteria. In the present study, sequence and structure-based properties of LPs in fungi and bacteria are compared. These properties include pseudo amino acid composition (PseAAC), physicochemical properties and the secondary structure. Autodock 4 has been used for docking between LiPs and lignan. The motifs of LiP were predicted by MEME tool. Statistical analysis and Multinomial Naïve Bayes (MNB) algorithm were used for the classification of two LiP protein groups. The results demonstrated that molecular weight, isoelectric point, aliphatic, extinction coefficient and random coil percentage of LiPs in fungi and bacteria were significantly different between these two groups. The classification of these two groups based on the concept of PseAAC showed over 80% accuracy. The binding free energy between bacterial LiPs and lignan is significantly more than fungi LiP and ligand. The aliphatic and instability of most important motifs of bacteria and fungi were significantly different. In conclusion, the results indicated that computational techniques could provide useful information for comparing fungal and bacterial LiPs. These results can also explain that there is a relationship between efficacy and physicochemical properties of LiPs.

Effects of Organic Molecules with Different Structures and Absorption Bandwidth on Modulating Photoresponse of MoS2 Photodetector.

Organic dye molecules possessing modulated optical absorption bandwidth and molecular structures can be utilized as sensitizing species for the enhancement of photodetector performance of semiconductor via photoinduced charge transfer mechanism. MoS2 photodetector were modified by drop-casting of methyl orange (MO), rhodamine 6G (R6G), and methylene blue (MB) with different molecular structures and extinction coefficients, and enhanced photodetector performance in terms of photocurrent, photoresponsity, photodetectivity, and external quantum efficiency were obtained after modification of MO, R6G, and MB, respectively. Furthermore, dyes showed different modulating abilities for photodetector performance after combination with MoS2, mainly due to the variation of molecular structures and optical absorption bandwidth. Among tested dyes, deposition of MB onto monolayer MoS2 grown by CVD resulted in photocurrent ∼20 times as high as pristine MoS2 due to favorable photoinduced charge transfer of photoexcited electrons from flat MB molecules to the MoS2 layer. Meanwhile, the corresponding photoresponsivity, photodetectivity, and an external quantum efficiency are 9.09 A W(1-), 2.2 × 10(11) Jones, 1729% at 610 nm, respectively. Photoinduced electron-transfer measurements of the pristine MoS2 and dye-modified MoS2 indicated the n-doping effect of dye molecules on the MoS2. Additionally, surface-enhanced Raman measurements also confirmed the direct correlation with charge transfer between organic dyes and MoS2 taking into account the chemically enhanced Raman scattering mechanism. Present work provides a new clue for the manipulation of high-performance of two-dimensional layered semiconductor-based photodetector via the combination of organic dyes.

(Invited) Insight into D-a-Pi-a Featured Organic Sensitizers

The practical application of DSSCs requires further improvements in the power conversion efficiency and long term stability. Recently, we have systematically studied a novel concept of D−A−π−A model for the molecular engineering of organic photosensitizers. We highlights recent advance in the D−A−π−A based photosensitizers, specifically focusing on the mechanism of efficiency and stability enhancements. Also we take insight into the additional acceptor as well as the trade-off of long wavelength response. The basic principles are involved in the molecular engineering of efficient D−A−π−A sensitizers, providing a clear road map how to rationally extend the response wavelength, enhance molecular extinction coefficients, and step by step optimize photovoltaic efficiency. Reference s (a) Y. Z. Wu, W. H. Zhu, Chem. Soc. Rev. 2013, 42, 2039–2058 (Review article); (b) Y. Z. Wu, W. H. Zhu, S. M. Zakeeruddin, M. Grätzel, ACS App l. Mat er. Interfaces 2015, 7, 9307−9318. (Spotlight on Applications).(a) Y. S. Xie, Y. Y. Tang, W. J. Wu, Y. Q. Wang, J. C. Liu, X.Li, H. Tian, W. H. Zhu, J. Am. Chem. Soc. 2015, 137, 14055−14058; (b) Y. S. Xie, W. J. Wu, H. B. Zhu, J. C. Liu, W. W. Zhang, H. Tian, W. H. Zhu, Chem. Sci. 2015, DOI: 10.1039/C5SC02778K.(a) W. H. Zhu, Y. Z. Wu, S. T. Wang, W. Q. Li, X. Li, J. Chen, Z.-S. Wang, H. Tian, Adv. Funct. Mater. 2011, 21, 756–763; (b) Y. Z. Wu, X.Zhang, W. Q. Li, Z. S. Wang, H. Tian, W. H. Zhu, Adv. Energy Mater. 2012, 2, 149–156; (c) Y. Z. Wu, M. Marszalek, S. M. Zakeeruddin, Q. Zhang, H.Tian, M. Grätzel, W. H. Zhu, Energy Environ. Sci. 2012, 5, 8261–8272; (d) W. Q. Li, Y. Z. Wu, X, Li, Y. S. Xie, W. H. Zhu, Energy Environ. Sci. 2011, 4, 1830–1837.(a) K. Pei, Y. Z. Wu, A. Islam, S. Q. Zhu, L. Y. Han, Z. Y. Geng, W. H. Zhu, J. Phys. Chem. C 2014, 118, 16552−16561; (b) H. B. Zhu, Y. Z. Wu, J. C. Liu, W. W. Zhang, W. J. Wu, W. H. Zhu, J. Mater. Chem. A, 2015, 3, 10603–10609; (c) Q. P. Chai, W. Q. Li, J. C. Liu, Z. Y. Geng, H. Tian, W. H. Zhu, Scientific Reports 2015, 5, 11330; (d) H. B. Zhu, B. Liu, J. C. Liu, W. W. Zhang, W. H. Zhu, J. Mater. Chem. C 2015, 3, 6882−6890.(a) Q. P. Chai, W. Q. Li, Y. Z. Wu, K. Pei, J. C. Liu, Z. Y. Geng, H. Tian, W. H. Zhu, ACS Appl. Mater. Interfaces 2014, 6, 14621–14630; (b) K. Pei, Y. Z. Wu, A. Islam, Q. Zhang, L. Y. Han, H. Tian, W. H. Zhu, ACS Appl. Mater. Interfaces 2013, 5, 4986–4995; (c) W. Q. Li, Y. Z. Wu, Q. Zhang, H. Tian, W. H. Zhu, ACS Appl. Mater. Interfaces 2012, 4, 1822−1830.

Pep-Calc.com: a set of web utilities for the calculation of peptide and peptoid properties and automatic mass spectral peak assignment.

The ability to calculate molecular properties such as molecular weights, isoelectric points, and extinction coefficients is vital for scientists using and/or synthesizing peptides and peptoids for research. A suite of two web utilities: Peptide Calculator and Peptoid Calculator, available free at http://www.pep-calc.com, are presented. Both tools allow the calculation of peptide/peptoid chemical formulae and molecular weight, ChemDraw structure file export and automatic assignment of mass spectral peaks to deletion sequences and metal/protecting group adducts. Peptide Calculator also provides a calculated isoelectric point, molar extinction coefficient, graphical peptide charge summary and β-strand contiguity profile (for aggregation-prone sequences), indicating potential regions of synthesis difficulty. In addition to the unique automatic spectral assignment features offered across both utilities, Peptoid Calculator represents a first-of-a-kind resource for researchers in the field of peptoid science. With a constantly expanding database of over 120 amino acids, non-natural peptide building blocks and peptoid building blocks, it is anticipated that Pep-Calc.com will act as a valuable asset to those working on the synthesis and/or application of peptides and peptoids in the biophysical and life sciences fields.