Ferreira, Misaeldos Santos, Miria C.Kreuz, AdrianSchneider, Felipe S. S....
14页查看更多>>摘要：Dyes presenting electron-accepting nitrophenyl and electron-donating phenolate groups have been used in the recent years as solvatochromic probes to investigate the polarity of solvents. Although several substituents in the phenolate have been used in studies involving these dyes, the use of tert-butyl groups has not yet been explored for these compounds. Bulky tert-butyl groups in the structure of these probes could bring interesting results because they make the dyes more lipophilic and hinder the formation of hydrogen bonds with hydrogen bond donating solvents. In this study, eight 2,6-di-tert-butylphenols were synthesized and characterized. They were then deprotonated to generate the corresponding phenolate dyes, which exhibited reverse solvatochromism. TD/ DFT calculations were performed, being shown that the longest wavelength absorption bands of the dyes are due to pi-pi* transitions, with an intramolecular charge transfer from the 2,6-di-tert-butylphenolate to the 4-nitrophenyl group. Data indicated that the overall nature of the excitation is the same in all cases, and the differences registered between experimental and theoretical data suggest that a synergetic effect in the solvation of the probes involving many solvent molecules may take place, which can widen the gap between HOMO and LUMO. The tert-butyl groups play an important role in the nature of dye-solvent interactions. Molecular dynamics simulations demonstrated the effect of the tert-butyl groups in hindering hydrogen bonding between the phenolate group and methanol and water solvent molecules, with a more structured solvation shell being observed on the nitro substituent of the probes. In conclusion, the investigation carried out showed that the presence of tert-butyl groups in the electron-donor phenolate groups tunes the types of interactions between the probe and the solvent. This can occur through changes in the molecular and electronic structure of the probe or be a result of steric hindrance, which makes the interaction of the solvent with the oxygen of the donor phenolate group more difficult.
原文链接:
NSTL
Elsevier
Long, HaijunGuo, DeWang, LiyuanLiu, Zitong...
7页查看更多>>摘要：A vinyl bridged 1,4,5,8-Naphthalenetetracarboxylic diimide (NDI) dimer, DNV was synthesized, which exhibits relatively strong Aggregation Induced Emission Enhancement (AIEE) behaviour with absolute quantum yield of 13.6%, as well as wide Aggregation Induced Chromism (AIC) phenomenon (over 100 nm), from green to orange emission. The density functional theory (DFT) and coupled cluster calculations reveal a unique twisted packing mode of DNV in its aggregated state, and mild intermolecular CT between the stacked DNV molecules was also observed. This J-aggregation like molecular arrangement and the net CT might contribute to the long wavelength emission. The bio-imaging capability of DNV is also examined by a living cell experiment.
原文链接:- NSTL
- Elsevier
Hu, YingShao, LixiaFan, YaoLu, Lingmin...
8页查看更多>>摘要：Due to their analog chemical structures and trace amounts, the distinguishment of tea polyphenols has always been an important but difficult challenge. In this paper, a novel sensing strategy NapB-MR by combining boronic acid-based sensor NapB with pH indicator (methyl red, MR) was constructed to colorimetrically identify different tea polyphenols. Gallic acid (GA), methyl gallate (MG), epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and epigallocatechin gallate (EGCG) were selected as analytes, which represent the majority of the polyphenols present in green tea. Due to the pH change profile induced by boronic ester formation, methyl red was applied to reflect the difference by exhibiting a unique colorimetric response towards each tea polyphenol. In combination with the Partial Least Squares Discriminant Analysis (PLSDA) model, the discrimination of six tea polyphenols were successfully carried out. In addition, quantitatively detection of each tea polyphenol could be achieved by coupling with UV-Vis spectroscopy, and low detection limits were obtained. Most importantly, the NapB-MR was successfully applied to classify green tea samples within different categories and grades with an identification rate of 100%. Therefore, the proposed sensing strategy can be a promising method for analog detection that can meet the increasing demand from consumers for the discrimination of polyphenol-related natural products.
原文链接:- NSTL
- Elsevier
Perry, Joseph W.Maury, OlivierAndraud, ChantalPascal, Simon...
8页查看更多>>摘要：Amino-heptamethines are highly conjugated cationic dyes featuring electronic absorption in the red region and strong near-infrared (NIR) fluorescence. Unlike their parent chloro-heptamethine cyanines, the substitution of the central position of their polymethine skeleton with an amine confers them a high Stokes shift. This work reports the synthesis of amino-heptamethines and the investigation of their optical properties, including two photon absorption in the NIR and short-wave infrared (SWIR) ranges, which has been overlooked for such chromophores so far. Their structures were tailored, introducing selected substitutuents on the indolenine moieties to modulate their hydrophobic/hydrophilic balance and investigate their potential as NIR-to-NIR two photon probes for the bio-imaging of living cells.
原文链接:- NSTL
- Elsevier
Ran, HuijuanLi, FeiZheng, RongZhang, Hailu...
8页查看更多>>摘要：Exploring the polarity change of organic field-effect transistors (OFETs) based on organic semiconductors through the molecular orbital distribution is a challenging work. In this study, we present two dithienocoronene diimide (DTCDI)-derived isomeric triads end-capped with azulene (DTCDI-B2Az and DTCDI-B6Az), which were designed and synthesized by connecting two azulene units at 2-position of five-membered ring (DTCDI-B2Az) or 6-position of seven-membered ring (DTCDI-B6Az) to the pi-conjugated electron-deficient DTCDI-core, respectively. The two isomeric triads show different molecular structure, electronic structure, optical and electrochemical properties. DTCDI-B2Az features the lowest unoccupied molecular orbital (LUMO) energy levels (-3.81 eV) and the highest occupied molecular orbitals (HOMO) energy levels (-5.80 eV), and meanwhile the LUMO/HOMO orbital distributing over the whole molecule, which facilitates electron/hole injection and transport under ambient conditions. However, DTCDI-B6Az possesses a LUMO/HOMO energy levels (-4.20/-6.02 eV) and its HOMO orbital is localized on two end-capping azulene units that can decrease the electron transfer barrier for more effective electron injection, and simultaneously suppress the hole injection and transfer. The OFET devices based on the two triads were fabricated by solution-processed method using bottom-gate top contact (BGTC) device structure. For DTCDI-B2Az, air-stable ambipolar transport characteristics were achieved with the highest hole/electron mobilities of 5.40 x 10(-4) and 1.83 x 10(-2) cm(2) V-1 s-( 1), respectively. However, for DTCDI-B6Az, air-stable unipolar n-type performances were obtained with the highest electron mobility of 1.56 x 10(-2) cm(2) V-1 s(- 1). Overall, this study demonstrates the polarity of OFETs was changed with the DTCDI-derived triads constructed by changing the connection position of the end-capped azulene group to the pi-conjugated electron-deficient DTCDI-core.
原文链接:- NSTL
- Elsevier
Zhang, BinjieLiao, PengHuang, JiarongFan, Cailing...
6页查看更多>>摘要：As an essential amino acid, arginine (Arg) is of many biological significances. However, the chemoselective detection of Arg using fluorescent techniques remain challenging. Here, a 1,1 & PRIME;-bi-2-naphthol (BINOL)-based fluorescent probe has been synthesized and responds chemoselectively to Arg to give strong fluorescence enhancement within a minute. The probe can report the concentration of Arg in a large window from 10 mu M to 5 mM. UV irradiation provides a qualitative method for Arg detection. The fluorescence of the formed imine product can be turned off again by either acid or base. Based on those findings, a simple fluorescence OFF -ON-OFF device has been made for the fast detection of Arg.
原文链接:- NSTL
- Elsevier
Pakhomov, Alexey A.Kim, Eleonora E.Kononevich, Yuriy N.Ionov, Dmitriy S....
8页查看更多>>摘要：A series of multifluorophore compounds with two, four, six and eight BODIPY residues linked to a siloxane core via a flexible spacer was synthesized. An increasing number of BODIPY units caused an enhanced propensity to chromophore aggregation with characteristic photophysical effects evoked by the aggregation. The increase in the number of fluorophores additionally resulted in considerable increase in molar extinction coefficient. Meanwhile, a slight drop of the extinction coefficient as calculated per a single chromophore was detected. Multifluorophore conjugates showed a significant broadening of fluorescence emission bands in polar solvents and a substantial decrease in the fluorescence quantum yield due to the aggregation-caused quenching. Time resolved fluorescence measurements of multifluorophore compounds in different solvents showed that the fluorescence decays have a multiexponential character and strongly depend on the number of fluorophores in the conjugate, polarity/viscosity of the solvent and the detection wavelength.
原文链接:- NSTL
- Elsevier
Vikneshvaran, SekarJang, Jae WoongPham, Nguyet N. T.Park, Se Jeong...
9页查看更多>>摘要：Numerous research endeavors have focused on the near-infrared (NIR) absorption properties and applications of polymethine dyes. Herein, we synthesize two heptamethine pyrylium dyes, TBCY-5 and TBCY-6, containing 5- and 6-membered, respectively, rings in the pi-conjugated bridge, thus producing NIR dyes with maximum absorption exceeding 1000 nm. The effect of counter anions on the NIR absorption property was examined by exchanging perchlorate (ClO4) anions with bistriflimide (TFSI) anions. TBCY dyes with TFSI possessed good solubility and a high molar extinction coefficient compared to the dyes with ClO4. TBCY-5 and TBCY-6 showed negative solvatochromism, exhibiting a hypsochromic shift of the NIR absorption in polar solvents. Photothermal experiments revealed that TBCY-5 and TBCY-6 were suitable as efficient photothermal materials.
原文链接:- NSTL
- Elsevier
Ilmi, RashidZhang, DanyangTensi, LeonardoAl-Sharji, Houda...
12页查看更多>>摘要：A series of tetrakis lanthanide complexes with the general formula [Ln(hfaa)(4)](-)(DpaH)(+) [Ln = (Sm-1), (Eu-1) and (Tb-1)], hfaa = hexafluroacetylacetonate and Dpa - 2,2 '-dipyridylamine] has been synthesized by the reaction of LnCl3, hfaa and Dpa in the presence of ammonia solution (25%). The complexes have been characterized by analytical and spectroscopic methods. The solution molecular structure of the complexes was elucidated by one- and two-dimensional NMR spectroscopy which shows that the DpaH+ cation retains a close interaction with the lanthanide anion in solution. The crystal structure of Eu-1, determined by single crystal Xray diffraction, confirms this intermolecular interaction in the solid-state through a N-HMIDLINE HORIZONTAL ELLIPSISO hydrogen bond of 2.187 A. In the [Eu(hfaa)(4)]- anion the EuO8 coordination polyhedron has a distorted triangular dodecahedron geometry with approximate D-2d-symmetry around the metal centre. Photophysical, thermal, and electroluminescent properties of the complexes have been investigated. The Sm-1 and Eu-1 complexes displayed efficient typical red emission with a sizeable photoluminescence quantum yield (PLQY) while Tb-1 displayed near-white light emission. The complexes have been used as dopants to fabricate single- and double-emitting layer (EML) OLEDs through the thermal evaporation method. At the optimum doping concentration, double-EML Eu-1 based device displayed orange electroluminescence (EL) with a brightness (B) of 417 cd/m(2) and very low Vturn-on = 3.4 V. Interestingly, the Sm-1 based single-EML device exhibited pure red emission with the Commission internationale de l'e acute accent clairage [(CIE)(x,y) = 0.613, 0.321], which is rare. The Sm-1 based device performance [B =145 cd/ m(2), current efficiency (eta(c)) = 0.35 cd/A, power efficiency (eta(p)) = 0.15 lm/W with an external quantum efficiency (EQE) = 0.3% and Vturn-on = 7.1 V] surpassed that of the only reported Sm-based single red-OLED (R-OLED).
原文链接:- NSTL
- Elsevier
Wang, Dong-HuiChen, Li-JianZhao, XuYan, Xiu-Ping...
9页查看更多>>摘要：Photosensitizers with organelle targeting play a vital role in image-guided photodynamic therapy (PDT). However, photosensitizers with the ability for dual-organelle targeting and dual-color emission are still lacking. Rational design of such photosensitizers with dual-organelle targeting and dual-color emission characteristics is of great significance for efficient enhancement of the performance of theranostics, but remains a challenge. Here we show a rational design to construct a dual organelle-targeted photosensitizer with dual-color emission by introducing cyano groups. To this end, two new photosensitizers TPA-2Py+ and TPA-2PyA+ with the electron donor (D: triphenylamine, TPA)-pi bridge (pi: benzene ring)-electron acceptor (A: vinyl/cyanovinyl pyridinium, Py/PyA) (D-pi-A) structure were synthesized. Both of them exhibit effective singlet oxygen generation due to the strong D-pi-A strength. TPA-2Py+ could light up the mitochondria of HeLa cells with near-infrared (NIR) emission. However, TPA-2PyA+ molecule possesses two additional cyano groups compared with TPA-2Py+, and enabled simultaneous locating into the lysosome and nucleolus with NIR and green fluorescence, respectively. Meanwhile, TPA-2PyA+ not only exhibited the ability to kill the cancer cells under light irradiation, but also to self-report the cell death in PDT via observing the change of emission color. This study offers an effective way for developing multifunctional photosensitizers for cancer theranostics.
原文链接:- NSTL
- Elsevier
