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Pyronin-9-thione (PY-S) is a key synthetic intermediate to develop various fluorescent probes for biological labeling and imaging. We developed a facile synthesis of PY-S from pyronin with a high yield up to 90%. The investigation of the reaction mechanism disclosed that the trisulfur radical anion (S3˙−) played a key role in the formation of the CS bond. The new established methodology was proved to have a short reaction time, operation easiness, and low toxicity and is suitable for the gram-scale synthesis of PY-S.

Fish morphological phenotypes are important resources in artificial breeding, functional gene mapping, and population-based studies in aquaculture and ecology. Traditional morphological measurement of phenotypes is rather expensive in terms of time and labor. More importantly, manual measurement is highly dependent on operational experience, which can lead to subjective phenotyping results. Here, we developed 3DPhenoFish software to extract fish morphological phenotypes from three-dimensional (3D) point cloud data. Algorithms for background elimination, coordinate normalization, image segmentation, key point recognition, and phenotype extraction were developed and integrated into an intuitive user interface. Furthermore, 18 key points and traditional 2D morphological traits, along with 3D phenotypes, including area and volume, can be automatically obtained in a visualized manner. Intuitive fine-tuning of key points and customized definitions of phenotypes are also allowed in the software. Using 3DPhenoFish, we performed high-throughput phenotyping for four endemic Schizothoracinae species, including Schizopygopsis younghusbandi, Oxygymnocypris stewartii, Ptychobarbus dipogon, and Schizothorax oconnori. Results indicated that the morphological phenotypes from 3DPhenoFish exhibited high linear correlation (>0.94) with manual measurements and offered informative traits to discriminate samples of different species and even for different populations of the same species. In summary, we developed an efficient, accurate, and customizable tool, 3DPhenoFish, to extract morphological phenotypes from point cloud data, which should help overcome traditional challenges in manual measurements. 3DPhenoFish can be used for research on morphological phenotypes in fish, including functional gene mapping, artificial selection, and conservation studies. 3DPhenoFish is an open-source software and can be downloaded for free at https://github.com/lyh24k/3DPhenoFish/tree/master.

Background: Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that play a key role in both physiological and pathological tissue degradation. MMPs have reportedly shown great potentials in the degradation of the Extracellular Matrix (ECM), have shown great potentials in targeting bioactive and imaging agents in cancer treatment. MMPs could provoke Epithelial to Mesenchymal Transition (EMT) of cancer cells and manipulate their signaling, adhesion, migration and invasion to promote cancer cell aggressiveness. Therefore, targeting and particularly inhibiting MMPs within the tumor microenvironment is an effective strategy for cancer treatment. Based on this idea, different MMP inhibitors (MMPIs) have been developed to manipulate the tumor microenvironment towards conditions appropriate for the actions of antitumor agents. Studies are ongoing to improve the selectivity and specificity of MMPIs. Structural optimization has facilitated the discovery of selective inhibitors of the MMPs. However, so far no selective inhibitor for MMP-7 has been proposed. Aims: This study aims to comprehensively review the potentials and advances in applications of MMPs particularly MMP-7 in targeted cancer treatment approaches with the main focus on targeted drug delivery. Different targeting strategies for manipulating and inhibiting MMPs for the treatment of cancer are discussed. MMPs are upregulated at all stages of expression in cancers. Different MMP subtypes have shown significant targeting applicability at the genetic, protein, and activity levels in both physiological and pathophysiological conditions in a variety of cancers. The expression of MMPs significantly increases at advanced cancer stages, which can be used for controlled release in cancers in advance stages. Methods: Moreover, this study presents the synthesis and characteristics of a new and highly selective inhibitor against MMP-7 and discusses its applications in targeted drug delivery systems for therapeutics and diagnostics modalities. Results: Our findings showed that the structure of the inhibitor P3’ side chains play the crucial role in developing an optimized MMP-7 inhibitor with high selectivity and significant degradation activities against ECM. Conclusion: Optimized NDC can serve as a highly potent and selective inhibitor against MMP-7 following screening and optimization of the P3’ side chains, with a Ki of 38.6 nM and an inhibitory selectivity of 575 of MMP-7 over MMP-1.

Both reactive oxygen species (ROS) and reactive nitrogen species (RNS) are inevitably produced during normal human metabolism. Various ROS and RNS together form tangled networks that play important roles in many physiological and pathological processes. Here we used 1,8-naphthalene diamine as a reactive group to develop a fluorescent probe, N-[2-(6-phenylethynyl)quinolinylmethyl]-1,8-diamino naphthalene (QBN), for HOCl and NO. QBN showed a “turn-on” fluorescent response at 464 nm to HOCl in the range of 0–75 μM with rapid responding time (10 s) and detection limit (0.11 ± 0.03 μM). Furthermore, a “turn-on” fluorescent responses at 512 nm to NO in the range of 0–40 μM with responding time (20 s) and detection limit (25.7 ± 3.4 nM) was found. The response mechanisms of QBN to HOCl and NO were discussed based on mass analysis of the different products. The dual-channel probe was then successfully applied for simultaneous imaging of both exogenous and endogenous HOCl and NO in live cells.

Traditional seed and fruit phenotyping are mainly accomplished by manual measurement or extraction of morphological properties from two-dimensional images. These methods are not only in low-throughput but also unable to collect their three-dimensional (3D) characteristics and internal morphology. X-ray computed tomography (CT) scanning, which provides a convenient means of non-destructively recording the external and internal 3D structures of seeds and fruits, offers a potential to overcome these limitations. However, the current CT equipment cannot be adopted to scan seeds and fruits with high throughput. And there is no specialized software for automatic extraction of phenotypes from CT images. Here, we introduced a high-throughput image acquisition approach by mounting a specially designed seed-fruit container onto the scanning bed. The corresponding 3D image analysis software, 3DPheno-Seed&Fruit, was created for automatic segmentation and rapid quantification of eight morphological phenotypes of internal and external compartments of seeds and fruits. 3DPheno-Seed&Fruit is a graphical user interface design and user-friendly software with an excellent phenotype result visualization function. We described the software in detail and benchmarked it based upon CT image analyses in seeds of soybean, wheat, peanut, pine nut, pistachio nut and dwarf Russian almond fruit. R2 values between the extracted and manual measurements of seed length, width, thickness, and radius ranged from 0.80 to 0.96 for soybean and wheat. High correlations were found between the 2D (length, width, thickness, and radius) and 3D (volume and surface area) phenotypes for soybean. Overall, our methods provide robust and novel tools for phenotyping the morphological seed and fruit traits of various plant species, which could benefit crop breeding and functional genomics.

Venlafaxine (VEN), a first-line antidepressant, and Zuojin Pill (ZJP), a common Chinese herbal medicine consisting of Rhizoma Coptidis and Fructus Evodiae, have high likelihood of combination usage in depression patients with gastrointestinal complications. ZJP exhibits inhibitory effects on recombinant human cytochrome P450 isoenzymes (rhCYPs), especially on CYP2D6, while VEN undergoes extensive metabolism by CYP2D6. From this prospective, we for the first time investigated the influence of ZJP on the metabolism of VEN in vitro and in rats. In this study, ZJP significantly inhibited the metabolism of VEN in both rat liver microsomes (RLM) and human liver microsomes (HLM); meanwhile, it inhibited the O-demethylation catalytic activity of RLM, HLM, rhCYP2D6*1/*1, and rhCYP2D6*10/*10, primarily through CYP2D6, with IC50 values of 129.9, 30.5, 15.4, and 2.3 μg/mL, respectively. Furthermore, the inhibitory effects of ZJP on hepatic metabolism and pharmacokinetics of VEN could also be observed in the pharmacokinetic study of rats. The AUC0-24h of VEN and its major metabolite O-desmethylvenlafaxine (ODV) increased by 39.6% and 22.8%, respectively. The hepatic exposure of ODV decreased by 57.2% 2h after administration (P = 0.014). In conclusion, ZJP displayed inhibitory effects on hepatic metabolism and pharmacokinetics of VEN in vitro and in rats mainly through inhibition of CYP2D6 activity. The human pharmacokinetic interaction between ZJP and VEN and its associated- clinical significance needed to be seriously considered.

As a structural analogue of pyridylthiazole, 2-(2-benzothiazoyl)-phenylethynylquinoline (QBT) was designed as a fluorescent probe for Hg(II) based on an intramolecular charge transfer (ICT) mechanism. The compound was synthesized in three steps starting from 6-bromo-2-methylquinoline, with moderate yield. Corresponding studies on the optical properties of QBT indicate that changes in the fluorescence ratio of QBT in response to Hg(II) could be quantified based on dual-emission changes. More specifically, the emission spectrum of QBT before and after interactions with Hg(II) exhibited a remarkable red shift of about 120 nm, which is rarely reported in ICT-based fluorescent sensors. Finally, QBT was applied in the two-channel imaging of Hg(II) in live HeLa cells.

Polydiacetylenic complex films were prepared using 10,12-pentacosadiynoic acid (PCDA) and para-xylenediamine (pXDA) upon acid-base interactions. The thermochromatic reversibility of the complex films was modulated by changing the mixed molar ratio (3 : 1, 2 : 1, and 1 : 1) of the two molecules. The corresponding conformational changes of the complex films were studied by ex situ FTIR analysis upon thermal stimulation for the first time. In addition, the binding specificities of α-, β-, and γ-cyclodextrins (CDs) with the films were studied, where the α-CDs can induce stronger red fluorescent emission of the films. These fundamental results may be useful for platforms that use these polydiacetylenic complex films as optoelectronic devices or chemical/biological sensors.

In the presented paper we investigated a 2-pyridylthiazole derivative, 4-phenyl-2-(2-pyridyl)thiazole (2-PTP), as the molecular fluorescent switches. It was firstly found that 2-PTP could perform a "turn-on" fluorescent sensing for Fe(III) with selectivity and reversibility. A 2:1 stoichiometry between 2-PTP and Fe(III) was determined according to the molar ratio method. The binding constant was evaluated as (1.90 ± 0.05) × 10(5) (L/mol)(2). The detection limit was found as 2.2 × 10(-7) M (S/N = 3). Secondly, 2-PTP also exhibited a pH-dependent dual-emission. The pK a(2-PTP-H(+)/2-PTP) value was then estimated as 2.0. To explain the identical emission at 479 nm of both the Fe(III) coordinated form and the protonated form of the ligand, we proposed a "locked" conformation. Finally, combining the two external stimuli as inputs, an OR logic gate was constructed using the fluorescent emission at 479 nm as the output channel.

2-Pyridylthiazole (2-PT) as a robust fluorophore has been applied in various fluorescent sensors. Based on the intramolecular charge transfer (ICT) process of 2-PT unit, we develop its new derivatives, 4-phenyl-5-phenylethynyl-2-(2-pyridyl)thiazole (4-PPT), as a ratiometric fluorescent sensor of Fe(III). 4-PPT exhibits fluorescence emission at 431 nm. Addition of Fe(III) can result in a red-shifted emission at 517 nm. The stoichiometry, binding constant, and detection limit are also investigated. Effects of Fe(III) on the fluorescence of 4-PPT could be removed by introduction of a strong chelator, and thus the reversibility is checked.

Hypochlorous acid, being one of reactive oxygen species (ROS), is essential to protect the body against invasion of pathogens. Excess of hypochlorous acid (HOCl) is believed to be in tight connection with various inflammation-related diseases. It remains a challenge to detect the ROS in physiological conditions (aqueous buffer and neutral pH) with selectivity. In the presented paper, we have synthesized a ferrocence-modified pyridylthiazole derivatives, 1,4-di{5-[(4’-ferrocenyl-2’-(4”-pyridyl)]thiazinyl}benzene (DFPT). Only HOCl could turn-on the fluorescence of DFPT with enhanced emission at 465 nm. Compared to the other reported HOCl sensors, DFPT could selectively detect HOCl with rapid response (< 60 s) in the aqueous buffer (pH = 7.0). The detection limit at pH = 7.0 was 0.7 μM according to the titration experiment.

A new fluorophore, 4-methyl-2-(2-pyridyl)-5-(2-thiophenyl)thiazole (2-PTT), was reported as a ratiometically fluorescent sensor of zinc(II) based on dual-emission with selectivity and sensitivity. Two emission bands at 440 and 497 nm were observed before and after addition of zinc(II), respectively. Job's plot disclosed the 1:1 stoichiometry between 2-PTT and zinc(II). The binding constant was evaluated as 2.09 × 10(5) M(-1) based on fluorescence titration experiment.

Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteases, which catalyze the cleavage of the extracellular matrix and thus are tightly associated with various physiological and pathological processes. The MMP family contains at least 28 members, with only MMP-1, -2 and -7 experimentally validated as targets for cancer therapy. As reported in previous studies, the inhibition of MMP-1 could result in various side effects, including musculoskeletal syndrome, which should be avoided. However, “broad spectrum” inhibitors, which typically utilize hydroxamic acid as a strong zinc-binding group (ZBG), have been unapproved due to their lack of selectivity. Further, because both MMP-1 and -7 have similar S′1 hydrophobic pockets, it remains a challenge to explore the selective inhibition of MMP-7 over -1 up to now. In the presented paper, we firstly introduced a nitro group as a ZBG in the inhibition of MMP. A series of nitro-based dipeptidic compounds were thus synthesized and evaluated as MMP inhibitors. Combined with the kinetic assay results and computational analysis of the binding mode of the inhibitors with the active sites of the enzymes, it was disclosed that a reasonable adjustment of the P′3 side chains of the nitro-based MMP inhibitors could improve selectivity for the inhibition of MMP-7 over MMP-1.

2-Benzyl-5-hydroxy-4-oxopentanoic acid 1 and its enantiomers were designed, synthesized and assayed for inhibitory activity against carboxypeptidase A (CPA, EC 3.4.17.1). To verify the role of the terminal hydroxyl group in 1 binding to CPA, 2-benzyl-5-benzyloxy-4-oxopentanoic acid 2 was also synthesized and evaluated. The inhibition constants show that both L- 1 and D- 1 were shown to have strong binding affinity with L- 1 being more potent than its enantiomer by 165-fold. On the other hand, the inhibition constant of 2 increases 4-fold comparing with that of 1 . In order to explore the exact binding mode of the hydroxyacteyl group of 1 to the active site zinc ion of CPA, we have solved the crystal structure of CPA complexed with L- 1 up to 1.85 A resolution. In CPA·L- 1 complex, the phenyl ring is fitted in the substrate recognition pocket at the S ′ 1 subsite, and the carboxylate forms bifurcated hydrogen bonds with the guanidinium moiety of Arg-145 and Arg-127 and a hydrogen bond with the phenolic hydroxyl of the down-positioned Tyr-248. The carbonyl oxygen of L- 1 does coordinate to the active site zinc ion of CPA as expectedly. Unexpectedly, the terminal hydroxyl group of L- 1 is engaged in hydrogen bonding with carbonyl oxygen of Ser-197 instead of coordinating to the active site zinc ion.

New electroluminescent materials, two DCM analogues 1,4-Bis[2-[3-(1,1-dicyan ovinyl)-5,5-dimethyl-cyclohexeneyl]vinyl]benzene ( 1 ) and 1,4-Bis{2-[3-(1,1-dicya novinyl)-5,5-dimethyl-cyclohexeneyl]vinyl}-2,5-di-(n-butoxy)benzene ( 2 ) with A-π-D-π-A structure were synthesized and characterized. Optical properties (UV–vis and fluorescence) were studied for both compounds according to the spectra analysis. Theoretical calculation and cyclic voltammetry were used to analyzed the frontier molecular orbital of the two compounds. The result suggest that compound 2 can used not only as dopants but also as host emission and electron injection materials. Two kinds of red OLEDs were fabricated using 2 and all the devices achieved good CIE coordinates.

Both enantiomers of 2-benzyl-5-bromo-4-oxopentanoic acid were prepared utilizing the diazo ketones as the key intermediates. The compounds were assayed for inhibitory activity against carboxypeptidase A (CPA, EC 3.4.17.1). The (R)-form is 260-fold more potent than the corresponding (S)-form. The finding that (R)-form, which belongs to the L-series, is mostly responsible for the inhibitory activity accords with the substrate specificity of CPA. For comparison, both the optical forms of 2-benzyl-4-oxopentanoic acid were also synthesized and evaluated as the inhibitors against CPA. These results reveal that the introduction of a bromo group at the α-position of ketones can significantly enhance the electrophilicity of the carbonyl group. Further molecular docking study suggested that the gem-diol form of the α-bromo ketone, which mimics the transition state in the CPA catalytic process, could chelate the zinc ion in the active site of CPA and thus result in the strong inhibition.

A solvent-sensitive highly fluorescent compound, N -[2-(1′,3′,4′,4′,5′,5′-hexafluorocyclopentenyl)]-4-(5-methoxy-thiazolyl)pyridine ( 1D ) was synthesized as an unexpected product of the reaction of 4-bromo-5-methoxy-2-(4-pyridyl)thiazole ( 1B ) with perfluorocyclopentene in the presence of n -BuLi. Primary mechanism of this reaction was proposed, and the photophysical properties of 1D in different solvents were studied.

A series of 1,4-distyrylbenzene derivatives containing 1,1-dicyanovinyl moieties were designed as poly-p-phenylenevinylene analogs to obtain the red electroluminescence assisted by the computational results. Based on the subsequent synthesis and optical studies, the present work indicated that introduction of 1,1-dicyano group as electron receptor in PPV skeleton could shift the electroluminescence significantly to the red region. The present work has shown a successful strategy to tune the emission of PPV analogs based on the theoretical design and organic synthesis.

Thermal Arndt–Eistert reactions of N‐tosyl cyclic α‐amino acids were studied to explore the preparation of α,β‐unsaturated esters bearing a terminal tosylamino group. For L‐N‐tosyl‐aziridine 2‐carboxylic acid and L‐N‐tosyl‐azetidine 2‐carboxylic acid, the corresponding (E)‐α,β‐unsaturated esters were obtained stereospecifically.

A pyrrolizidine alkaloid, (2S, 8S)‐2‐benzyl hexahydro‐pyrrodizin‐3‐one, was synthesized from (L)‐proline using diastereoselective benzylation as the key step. The absolute configuration of the target compound was confirmed through 2D H‐H COSY and H‐H NOESY spectra.

All four possible stereomers of 2-benzyl-3-methanesulfinylpropanoic acid were synthesized and evaluated as inhibitors for carboxypeptidase A to find that the isomer having the (2S,4S)-configuration is most potent followed by isomers of (2R,4S)- and (2S,4R)-configurations. The stereochemical preferences shown by the isomers of the inhibitor in binding to the enzyme suggest that the sulfoxide oxygen in the inhibitor fails to ligate the active site zinc ion but may form a hydrogen bond with the guanidinium moiety of Arg-127 like the carbonyl oxygen of scissile peptide bond of oligopeptide substrate of the enzyme does. It may thus be inferred that a sulfoxide moiety may serve as an isosterer of a carboxamide moiety.

Being a "lock-unlock" system, gated photochromism is generally applied in nondestructive readout for optical memory materials. In the presented paper, we successfully constructed molecular keypad locks by introduction of the gated photochromism. A series of diarylethenes compounds (DAEs) based on fluorescent 5-methoxy-2-pyridyl thiazoles, were prepared and then characterized as photochromic fluorescent switches. Protoantion of the reported DAEs resulted in both protonation-locked photo-reactivities, i.e., gated photochromism, and enhancement of fluorescence. Molecular keypad locks were then successfully constructed, which are also featured by "one-key" lock operation.

Zinc-binding groups (ZBGs) are exhaustively applied in the development of the new inhibitors against a wide variety of physiologically and pathologically important zinc proteases. Here the alpha-nitro ketone was presented as a new ZBG, which is a transition-state analog featured by the unique bifurcated hydrogen bonds at the active site of carboxypeptidase A based on the structural analysis. Introduction of a nitro group at the alpha-position of the ketone could provide more non-covalent interactions without loss of the abilities to form a tetrahedral transition-state analog.

A series of 2-(N-oxide pyridyl)-5-methoxythiazoles were synthesized and corresponding optical properties were also investigated. It is first found that a digital-type fluorescent responses in a sharp pH variation with dual-emission could be fulfilled based on a small fluorophore.

2-Substituted 3-nitropropanoic acids were designed and synthesized as inhibitors against carboxypeptidase A (CPA). (R)-2-Benzyl- 3-nitropropanoic acid showed a potent inhibition against CPA (K(i)=0.15 microM). X-ray crystallography discloses that the nitro group well mimics the transition state occurred in the hydrolysis catalyzed by CPA, that is, an O,O'-bidentate coordination to the zinc ion and the two respective hydrogen bonds with Glu-270 and Arg-127. Because the nitro group is a planar species, we proposed (R)-2-benzyl-3-nitropropanoic acid as a pseudo-transition-state analog inhibitor against CPA.

Thermal Arndt–Eistert reactions of N‐tosyl cyclic α‐amino acids were studied to explore the preparation of α,β‐unsaturated esters bearing a terminal tosylamino group. For L‐N‐tosyl‐aziridine 2‐carboxylic acid and L‐N‐tosyl‐azetidine 2‐carboxylic acid, the corresponding (E)‐α,β‐unsaturated esters were obtained stereospecifically.

A pyrrolizidine alkaloid, (2S, 8S)‐2‐benzyl hexahydro‐pyrrodizin‐3‐one, was synthesized from (L)‐proline using diastereoselective benzylation as the key step. The absolute configuration of the target compound was confirmed through 2D H‐H COSY and H‐H NOESY spectra.

In the title compound, C12H7I2N, the tricyclic aromatic ring system is essentially planar, with an r.m.s. deviation of 0.0272 Å. The two I atoms are marginally out of plane, with the C—I bonds angled at 3.9 (2) and 1.1 (2)° with respect to the planes of their respective benzene rings, above and below the plane of the carbazole ring system. No classical hydrogen bonds are observed in the crystal structure.

A series of nitro-based compounds were synthesized and evaluated as inhibitors against thermolysin (TLN). The binding modes of the nitro group at the active site of TLN were characterized based on the structural analysis of TLN-(R)-2-benzyl-3-nitropropionic amide complex, which was suggested as a pseudo-transition state analogue. Further structure–activity relationship studies disclosed that both the stereochemistry of the P1 chains and the bulkiness of the P2 0 substituents were crucial to the potent inhibition of TLN.

The fluorescence behaviours of a chemical-sensitive fluorescent molecule 1,2-di[5-methoxy-2-(2-pyridiyl)thiazoyl]ethyne (DMPTE) at different protonation and coordination states were studied. Upon addition of protons, metal ions and other chemicals, the fluorescent states can be switched reversibly. On the basis of the changes of fluorescence output signals from particular wavelengths in response to different combination sets of two particular external stimuli, the entire set of 2-bit Boolean binary logic functions were realized at the molecular level, including PASS 0, PASS 1, YES, NOT, OR, NOR, INHIBIT, IMPLICATION, AND, NAND, XOR, XNOR, and different logic functions were integrated reconfigurably within DMPTE. Besides, starting from the same initial state, a series of three-input logic gates and circuits were also constructed. Furthermore, the stepwise recognition process of DMPTE to different chemical input signals can also be utilized to distinguish different input sequences, thus a molecular keypad lock that authenticates three-digit password entries is indicated.

In rhe title compound, C28H20N2S4, the 1,3-dithiol-2-ylidene and 4,5-diazafluoren-9-one (dafone) groups are almost coplanar, making a dihedral angle of only 5.65 (4)°. The two benzyl groups are on different sides of the 1,3-dithiol-2-ylidene ring, forming a dihedral angle of 35.54 (2)°.

In the title compound, tetra­kis[μ3-2-(5-hydr­oxy-2-oxido­benz­yl­ideneamino)-2-methyl­propanolato]tetra­copper(II) meth­anol tetra­solvate, [Cu4(C11H13NO3)4]·4CH3OH, two Cu2 cores are linked by two μ3-bridging alkoxo O atoms to form a centrosymmetric dimer of dicopper(II) units. Two Cu atoms coordinate to the NO2 (a phenolic O atom, an alcoholic O atom and an imine N atom) chelator unit of one ligand and an alcohol O atom of the other ligand, forming a distorted planar coordination configure. The remaining Cu atoms coordinate in a pyramidal geometry. The distorted basal plane is also formed by the N2O unit and the alcohol O atom from the second ligand, while an alcohol O atom from a third ligand occupies the axial position.

A novel fluorescent chemosensing material (2-MPT-SBA-15) for multianalyte detection in water was prepared through the functionalization of mesoporous silica (SBA-15) with a fluorescent chromophore, 5-methoxy-2-thiazoles (2-MPT). The characterization of the obtained material 2-MPT-SBA-15 shows that the organized structure is preserved after the post-grafting procedure. This hybrid material not only displayed pH sensitive fluorescent behavior with a dual-emission in the range of 1 to 5.7, but is also an optical sensor for the sensitive and selective detection of Cu2+ ions in water. Furthermore, both the sensing detection of pH and Cu2+ are very fast and reproducible.

A new series of fluorophores, 5-methoxy-2-(2-, 3- or 4-pyridyl)thiazoles (2-, 3- or 4-MPT, respectively), were synthesized and their photophysical properties investigated. 2- and 4-MPT are highly fluorescent in polar solvents. Combined with theoretical calculations, studies of the excited state lifetimes in different solvents reveal that their fluorescence mainly results from the internal charge transfer excited state. Acidobasic properties of their ground states and excited states were studied with steady and transient fluorescence spectroscopy. 2- and 4-MPT displayed a pH sensitive fluorescent behavior with a dual-emission in the range 2 to 6 in an aqueous system.