A Pyrene-Tetrazole Fused Fluorescent Probe for Effective Real Time Detection Towards Aluminium Ion.

We constructed a novel-binding site for metal ion detection using a fused tetrazole ring conjugated with aminopyrene (R). The designed structure of the molecule was successfully synthesized and determined the probe's selectivity by testing various metal ions and found that the probe effectively detects Al3+ ion visually. Checked the sensing ability of the probe with different approaches (fluorimetric and colorimetric), and the effectiveness is double confirmed. The added Al3+ ion to R procured a rapid change in color from yellowish orange to colorless. Under the UV lamp, a turn-on blue fluorescence was observed after adding aluminium ion, whereas the probe was non-fluorescent before detecting aluminium ion. The probable interface of the probe with aluminium ion has also been expected from HRMS spectral analysis results. The probe's utility in real-time monitoring of Al3+ ion in water is confirmed by a simple test kit prepared using filter paper. The kit showed a possible naked-eye detection with a notable color change, and when checked, the aluminium ion detected test kit under a UV lamp showed blue fluorescence.

Effects of Xanthene Fluorophore on Light Physical Properties and their Dyeing Performance on Modacrylic Fabrics.

We designed the new xanthene dyes by introducing the donor and acceptor group of electrons in the 5' position of the carboxyphenyl ring. These synthesized dye molecules were identified using spectroscopy. And the photophysical studies, such as solvent optimization, were further explored before and after photodegradation of all synthesized dye compounds in both states (solution and solid). The resulting dyed modacrylic fabrics and measured their K/S values, reflectance (%), solid UV absorbance, and photoluminescence. All compounds are plotted on a chromaticity map in the pink region. During photodegradation, the stability of the molecule depends on the effect of the functional groups (donor to acceptor). In this case, ln[C/C0] (%) became the decreasing sequence from an electron donor to acceptor, as the electrons followed from the donation function group to the carboxylic function group. Therefore, the electron-accepting group dyes decompose rapidly during ultraviolet radiation.

Thermally Reversible Fluorans: Synthesis, Thermochromic Properties and Real Time Application.

In the present study, two fluoran molecules (TH1 and TH2) have been synthesized, and their reversible thermochromic properties have been investigated. This work demonstrates the thermochromic reversibility of the fluoran. Furthermore, the three-component mixtures that comprising fluorans (TH1/TH2), bisphenol-A (color developer), and methyl stearate a low melting solvent were used to examine the thermochromic behavior with sturdy heating and cooling rates and the thermochromic properties of the fluorans were detailed using UV-Vis, reflectance and FT-IR spectroscopic techniques. Finally, test strip similar to pH paper and acrylic fiber a versatile material used as thermal indicators also been successfully made from these two fluoran derivatives.

Synthesis, Spectral and Photophysical Properties of Anthracene Substituted Phthalocyanines; A Study as Polyurethane Electrospun Nanofibers.

We have designed and synthesized novel symmetrical anthracene substituted zinc(II), copper(II), cobalt(II) and nickel(II) phthalocyanines (PC1, PC2, PC3 and PC4) in this work. For this synthesis, we started from base-catalysed aromatic displacement reaction of 4-nitrophthalonitrile with 9-hydroxyanthracene. The resulting four phthalocyanines (PCs) have been fully characterized by a series of spectroscopic methods including electronic absorption, elemental analysis, MALDI-TOF mass, and IR spectroscopy. The aggregation behavior of these PCs was investigated in different concentrations of chloroform solution. Further thermal stability also investigated by TG analysis. Finally we successfully made phthalocyanine (PC1) blended polyurethane electrospun (ES) nanofibers.

Synthesis, Optical, Electrochemical and Theoretical Studies of New Multicyclic Substituted Phthalocyanines.

Here novel phenanthrenoxy and pyrenoxy substituted phthalocyanines were synthesized and fully characterized by general spectroscopic methods such as elemental analysis, 1H NMR, MALDI-TOF, FT-IR, UV-Visible absorption. The aggregation property of these phthalocyanines was investigated in CHCl3 and Triton X. Furthermore, electrochemical and DFT calculations were performed for these molecules.

"Turn-On" Fluorescent and Colorimetric Detection of Zn2+ Ions by Rhodamine-Cinnamaldehyde Derivative.

We report the design and synthesis of a novel chemosensor (Rh6G-Cin) rhodamine-based indicator for selective detection of Zn2+ ion. Rh6G-Cin displayed high selectivity towards Zn2+ from various metal ions, including Ca2+, Ag+, Cd2+, Co2+, Cu2+, Al3+, Zn2+, Cr3+, Ba2+, Fe2+, Fe3+, Gd3+, Hg2+, Mg2+, Mn2+, Nd3+, Pb2+, Sr2+ and Ni2+, and the resultant complex is [Rh6G-Cin-Zn2+]. The obvious change from colorless to pink upon the addition of Zn2+ could make it a suitable "naked eye" indicator for Zn2+. More significantly, the sensor displayed a remarkable colorless to yellowish green fluorescence switch in the presence of Zn2+ ions. The ring-opening mechanism of the rhodamine spirolactam was induced by Zn2+ binding, and the 3:1 stoichiometric structure between Rh6G-Cin and Zn2+ was adequately supported by the Job's plot evaluation, optical titration and 1H NMR results.

Optical Properties of 1,3-Bisdicyanovinylindane, an Electro-Acceptor, Attached Bisthienylethene Molecule.

An electron acceptor, 1,3-bisdicyanovinylindane, was attached to the skeleton of bisthienylethene. Photochromic behavior was investigated in THF. Under exposure of UVNisible light cycles, the solution color can be toggled between colorless and yellow. Good fatigue resistance and photo-/thermal-stability were demonstrated with acceptable degradation. A full-photo mode switch was established. Optimized structure and molecular orbital of ring-open and ring-closed isomers were calculated on the platform of DmoP. The photochromic behavior was further supported by the required distance between photocyclizing atoms in antiparallel conformation. The absorption spectra change derived from calculation was in agreement with the experimental results.

High Pseduo-Stoke's Shift of a Naphthalene-Bisindolylmaleimide Dye.

An energy transfer cassette was reported with energy donor and acceptor incorporated in one molecular. The two units (naphthalene and bisindolylmaleimide) were connected by covalent single bond. The intramolecular repulsion twisted the molecular conformation, thereby forcing the two units act as independent chromophores. Upon photoexcitation (λ = 280 nm), bright emission peak was observed around 583 nm. The intramolecular cascade energy transfer from the naphthalene moiety to the bisindolylmaleimide framework is efficient and the efficiency is estimated to be 86%, providing large pseudo-Stoke's shift (303 nm). At such a short separation, the orbital overlap interaction was completely isolated between chromophoric units. Computational study was carried out based on DFT. Further analysis of optimized structure and FMOs supports the efficient energy transfer in NBM. Favorable photophysical properties, such as efficient energy transfer, strong emission, and large Stoke's shift make it an attractive functional dye.

Spectral Switching of Naphthalimide-Coumarin Induced by F-.

A highly selective color sensor based on naphthalimide and coumarin was reported. Upon addition of F-, the solution color changed from pale yellow to deep blue. The sensor shows excellent selectivity against other common anions. The underlying mechanism for the color change is based on the deprotonation/protonation of the dye. Frontier molecular orbitals analysis gives further insight about the signaling mechanism.

A bisindolylmaleimide-naphthalimide building block for the construction of the energy transfer cassette.

Double build-in chromophores with naphthalimide and bisindolylmaleimide incorporating to one molecule were synthesized efficiently and characterized fully. Its spectral properties were investigated. Effective intramolecular energy transfer together with the strong emission in solution and solid state were discussed in terms of its electronic structures. Optimized structure and frontier molecular orbital were calculated based on D3(mol) platform. Obviously electron delocalization before and after excitation was observed according to the molecular orbital calculation, which corresponds to the mechanism of excitation energy transfer through space occurred in the donor-linker-acceptor molecular system. The opto-physical properties of the dye indicated potential application of electro-optical materials.

Synergistic integration of a rhodamine-labelled tripeptide into AIE-active fluorogenic probe: Enabling nanomolar detection of Al3+ ions through test strips, thin films, and Arduino-assisted optosensing platform.

Peptide-fluorophore conjugates (PFCs) have been expeditiously utilized for metal ion recognition owing to their distinctive characteristics. Selective detection and quantification of aluminum is essential to minimize health and environmental risks. Herein, we report the synthesis and characterization of a new chemoprobe with aggregation-induced emission characteristics by chemically conjugating rhodamine-B fluorophore with a tripeptide. The probe revealed ß-sheet secondary conformation in both solid and solution states, as confirmed by FT-IR, PXRD, and CD experiments. AIE characteristics of the probe in water-MeCN mixtures revealed the formation of spherically shaped nanoaggregates with an average size of 353 ± 7 nm, as confirmed by SEM, TEM, and DLS studies. The probe exhibited a large stokes shift (175 nm) and displayed selective colorimetric and fluorometric responses towards Al3+ ions with an extremely low detection limit (51 nm) and a fast response time (≤15 s). Comparative NMR studies confirmed the cleavage of spirolactam ring upon aluminum binding. The probe's practicality was enhanced through integration into test strips and thin films, allowing solid-phase detection of Al3+ ions. Furthermore, an RGB-Arduino enabled optosensing device has been developed to enable instant quantifiable analysis of aluminum concentrations in real-time conditions.

An ICT-based highly fluorescent isoquinoline scaffold for selective Hg(II) detection in real-water samples: Development of a smart, low-cost RGB-Arduino electronic platform.

Selective detection and quantification of Hg2+ ions is crucial to minimize health and environmental risks. Fluorescent organic small-molecule probes have been expeditiously utilized owing to their unique set of improved properties. However, isoquinoline core has not been extensively explored as a fluorescence platform partly due to synthetic challenges. Herein, a serendipitously discovered synthetic route to access a small yet highly functionalized novel isoquinoline-based probe, IQ is reported. The synthesis is achieved through the in-situ generation of ammonia, followed by intermolecular [5C + 1 N] aza-annulation reaction with a ketendithioacetal-based precursor, P-IQ. IQ displayed excellent recognition ability towards Hg2+ ions in H2O:ACN (99:1, v/v) via ICT-off fluorescent quenching behavior. Comparative FT-IR, 1H/13C NMR, mass spectral studies, and DFT analyses were carried out to validate the suggested mechanisms. Reversible studies confirm the secondary recognition effect of in-situ generated (IQ + Hg2+) complex on cysteine. The binding constant and LOD were estimated to be 3.7 × 104 M-1 and 0.86 µM, respectively. Further, IQ was utilized to evaluate the mercury ion content in real water samples demonstrating its effectiveness in water quality monitoring. The practical utility of IQ was further explored by developing TLC strips, Whatman filter-paper strips, and a low-cost, portable Arduino-based platform. Arduino microcontroller is interfaced with an RGB sensor to detect color changes and quantify mercury concentration w.r.t. RGB values.

Development of a novel sensory material for rapid detection of mercury ions in various water sources: Solution and solid-state analysis.

A xanthene propane nitrile-based sensor material was successfully prepared, and an attempt towards the preparation of polymer bead form was made for the sensitive or selective detection of mercury ions (Hg2+) in water. The sensor material in solution as well as in polymeric form showed amazing selectivity over other added metal ions with a naked eye color change, UV visible spectral and fluorescence spectral change, and a rapid and excellent color change from colorless to purple. The 1H NMR study exposed the probable binding site of the probe with the added mercury ion. In this study, the imine nitrogen and the C = O interact with the mercury ion, resulting in the ring opening of lactam with a vivid color change. The EDTA test was done to verify the reversible behavior of the probe and confirmed its reversibility by UV-visible and fluorescence spectral studies. The polymer bead made using this probe can be used as a tool for monitoring mercury ions in real time in different sources of water samples. The sensor molecule itself senses the mercury ion in its solid state by simple grinding and changes its color from pale yellow to deep purple. The sensor color change response is very rapid towards mercury detection, which is confirmed by the prepared test strip.

Optimizing cyanine dye properties for enhanced dyeing and inkjet printing on diverse Substrates: Photophysical and colorimetric investigations.

Cyanine-based cationic dyes with different substituents in the donor unit were easily synthesized using readily available starting materials. The prepared dye molecules were spectroscopically characterized by NMR, FT-IR, and HR-Mass, and their thermal stability was measured by TGA, DSC, and XRD. Based on the TGA and DSC measurements, it was concluded that all the dyes are thermally stable up to 200 °C. Also, powder XRD was studied for all dyes to identify the explicit crystallinity and morphological nature of the dyes. A dye dispersion solution was prepared for the proper dyeing of modacrylic fabric and the dyed fabric showed good color strength K/S for dyes R1, R2, and R6 and fragile color strength for R3, R4,and R5. These dyes are also used for printing on substrates like paper and fabric using ink-jet printing. These dyes were also used for transferability printing applications on various fabrics.

Synthesis and luminescent properties of a linear difluorene pyrazine (D-A-D) derivative as a selective indicator for a reversible acid-base vapour sensor.

We have synthesized a structure in which pyrazine is the core structure and fluorene derivatives are attached to both sides. Photo physical investigations such as aprotic solvents (Hexane to DMF) were carried out. A redshift was revealed from non-polar aprotic solvents to polar aprotic solvents. The luminescence intensity was gradually decreased, which is incredibly more complex towards changes in the solvent polarization than their UV/Vis absorption spectra. The compound showed a redshift from 445 nm to 473 nm when slowly increasing the water fraction (fw) from 0 to 30 %. Also, rising water fraction (fw > 40-90 %) effectively attenuated the instantaneous emission intensity was observed. At the same time, the intensity of the emission peak was reduced due to the TICT effect on fluorene and pyrazine rings due to enhanced solvent polarity. In addition, optically reversible acidofluorochromic properties were performed experimentally in both solvent and solid phases. For the acidic substances TFA and HF, which contain fluorine, new redshift peaks from 425 nm and 503 nm were observed upon reaction with the PDF solution, and the emission intensity was extinguished by more than 90 % and 60 %, respectively. Upon addition of TFA up to 1500 equal, the PDF mixture suffered from 50 % lower energy absorption intensity. The 1H NMR spectrum confirmed the proposed mechanism (TFA/TEA, ON-OFF-ON). Therefore, the present work presents a novel approach to fabricating ON-OFF-ON active-pull pyrazine scaffolds that can be used in DSEgens, referred to as "ON-OFF-ON" fluorescent sensors, for multifunctional applications.

Tailored fluorophore design: Enhancing selectivity for cyanide ion sensing in water and food samples, and innovative device development.

A rigid fluorophore unit of Julolidine/coumarin fused with an indolium-conjugated system was built for the immediate and effective recognition of cyanide ions in a 90 % aq. DMSO solution. The probes are capable of displaying better sensitivity/selectivity for the cyanide ion over a wide range of other interfering ions. The probe JI showed an instant colorimetric variation, whereas the modified probe JCI showed both colorimetric and fluorimetric variation with cyanide ion. The observed detection limit values indicated excellent sensitivity of the probe to the cyanide ion. HRMS and 1H NMR studies confirmed that the mechanism of detection of CN- is via the nucleophilic attack on the electron-deficient indolium moiety of the molecule. Moreover, the probes are well proficient in selective recognition of cyanide in various real time applications (test strips, electronic sensor kit, food and water sample analysis).

Design, synthesis and characteristics on novel D-pi-A dye chromophore: fluorochromism effects.

Recently, photophysical property with fluorescence function has been attracted and studied because there are promising potentials in academic and industrial applications. Organic materials having fluorescence effect, especially fluorochromism can be utilized in the sensing or probing with absorption/emission changes. Herein, the prepared dye chromophore can be changed to their optical properties with polar/non-polar environmental media. In this work, we synthesized a new fluorochromism dye, namely 5-[2-(4-diphenylamino-phenyl)-vinyl]-2,2-dimethyl-[1,3]dioxane-4,6-dione using 3-formyl triphenylamine and 2,2-dimethyl-[1,3]dioxane-4,6-dione. We investigated absorption and fluorescent emission in various solvent media. Furthermore, cyclovoltammogram was used to determine energy levels of HOMO/LUMO from their redox onset potentials. Measured energy levels of HOMO/LUMO were compared with the results of simulated computational calculation.

A novel fluorophore with multichromic effect and its application in LED light for the volatile vapor detection.

Successfully designed and synthesized diaryl maleimide DAM, and their structure was confirmed by mass spectroscopy and NMR techniques. They investigated their photophysical properties, such as solvatochromic and the aggregation effect of AIE/ACQ on the water/DMF ratio, and other studies of solid-state mechanofluorochromic, such as grinding, exposure to solvent fumes, hydrostatic pressures, and vapochromic. Interestingly, the solvent methods gave very similar results in both the dissolving phase and the vapor phase. For the solution state from hexane to CH2Cl2, a greenish-yellow to orange emission was observed. From hexane to dichloromethane, naked-eye colorimetric changes (from yellow to orange in a solid state) were observed. Very interesting results were obtained, the yellow solid was ground for 1 min, it turned into an orange color, and its wavelengths were red-shifted in both absorption and emission. Subsequently, the ground sample was exposed to diethyl ether vapors, which returned to the original green-yellow emission and absorption. The applied hydrostatic pressures (0-4Mpa) in DAM gave excellent red-shifted emission, and then their hydrostatic pressures were increased to 4-16 Mpa, and the red-shifted emission gradually decreased.

Highly emissions of TPA-linear based pyrazine derivatives with different mechanochromic luminosity.

We designed the TPA-based linear pyrazine derivatives of PP-1 and PP-2, synthesized using the conventional Suzuki cross-linking reaction. It was followed by photophysical studies such as aprotic solvent (Haxene to DMF). A red-shift was observed from the non-polar aprotic solvent to the polar aprotic solvent, and the emission intensity was gradually decreased. In addition, the Aggregation-induced emission (AIE) effect has been studied against the DMF/water addition of linear pyrazine compounds. It showed a classic aggregation-caused quenching effect (ACQ) and red-shifted at an increase of (fw) 0 to 40%. After this case, when the water fraction in these studies was increased by (fw) 50 to 90%, a blue shift and a mild AIE effect has occurred. And also, was investigated acidochromic effect of compounds PP-1 and PP-2 using TFA acid. Absorption and emission intensity were gradually reduced as the acid concentration increased for these studies, while the new peaks appeared red-shifted in the absorption spectrum. They were examined before and after exposure to UV light irradiation in the synthesized dye compounds.

A colorimetric and fluorescent chemosensor for Ni2+ based on donor-pi-acceptor charge transfer dye containing 2-cyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran acceptor and 4-bis(pyridin-2-ylmethyl)aminobenzene donor.

A new designed colorimetric and fluorescent dye chemosensor was synthesized, characterized and computationally calculated using MO theory calculation, which was based on donor-pi-acceptor electron charge transfer system. This particularly designed dye chemosensor displayed the selective Ni2+ ion chemo-sensing effects in optical properties with absorption and fluorescence emission. This dye chemosensor represented clear absorption spectra changes with Ni2+ ion and the dramatic fluorescence quenching effect with Ni2+ ion was determined. However it showed no significant optical spectra changes upon the addition of other metal ions such as Cd2+, Na2+, Mg2+, Pb2+, Fe2+, Fe3+, Ca2+, Cu2+, Hg2+, except Zn2+.