Highly sensitive AIEE active fluorescent probe for detection of deferasirox: extensive experimental and theoretical studies.

High concentrations of deferasirox (DFX) in living organisms cause hepatic, gastric and renal malfunctions. Therefore, it is significant to establish an accurate and efficient approach for the detection of deferasirox (DFX) to protect public health. Herein, we synthesized a thiourea-based diphenylacetamide probe MPT for the effective sensing of deferasirox through the fluorescence quenching phenomenon. The designed probe MPT shows a fluorescence quenching response toward deferasirox (DFX) through photo-induced electron transfer (PET). Furthermore, DFT studies were performed to support the experimental results. 1H-NMR titration experiment was used to explore the interaction type between probe MPT and DFX. The existence of non-covalent interactions was verified with spectroscopic studies that were assisted by NCI studies, QTAIM and SAPT0 analysis. Dynamic light scattering (DLS) analysis and scanning electron microscopy (SEM) were used to investigate the complexation of probe MPT with DFX. Moreover, the on-site solution phase and solid-state detection of DFX by probe MPT are executed. Additionally, the practical applications of probe MPT to sense DFX were also revealed in human plasma as well as in artificial urine samples.

A combined experimental and theoretical approach for doxycycline sensing using simple fluorescent probe with distinct fluorescence change in wide range of interferences.

Overuse of doxycycline (DOXY) can cause serious problems to human health, environment and food quality. So, it is essential to develop a new sensing methodology that is both sensitive and selective for the quantitative detection of DOXY. In our current research, we synthesized a simple fluorescent probe 4,4'-bis(benzyloxy)-1,1'-biphenyl (BBP) for the highly selective detection of doxycycline by through fluorescence spectroscopy. The probe BBP displayed ultra-sensitivity towards doxycycline due to Forster resonance energy transfer (FRET). Fluorescence spectroscopy, density functional theory (DFT), 1H NMR titration, UV-Vis, and Job's plot were used to confirm the sensing mechanism. The charge transfer between the probe and analyte was further examined qualitatively by electron density differences (EDD) and quantitively by natural bond orbital (NBO) analyses. Whereas the non-covalent nature of probe BBP towards DOXY was verified by theoretical non-covalent interaction (NCI) analysis as along with Bader's quantum theory of atoms in molecules (QTAIM) analysis. Furthermore, probe BBP was also practically employed for the detection of doxycycline in fish samples, pharmaceutical wastewater and blood samples.

Extensive optical and DFT studies on novel AIE active fluorescent sensor for Colorimetric and fluorometric detection of nitrobenzene in Solid, solution and vapor phase.

An electron rich isophthalamide based sensor IPA has been synthesized through a simple two-step reaction, containing noteworthy aggregation induced emission (AIE) properties. Considering the significant emission with λmax at 438 nm, sensor IPA has been employed for the sensing of nitrobenzene (NB) in solid, solution and vapor state with high sensitivity and selectivity. Sensor IPA showed noteworthy colorimetric and fluorometric quenching in fluorescence emission when exposed to NB. Small size of NB and involvement of photoinduced electron transfer (PET) lead to detection of NB down to 60 nM. IPA-NB interaction was studied through UV-Vis. spectroscopic studies along with fluorescence spectroscopy. Moreover, 1H and 13C NMR titration experiments provided additional support for determination of interaction type. Furthermore, by using density functional theory (DFT) calculations, thermodynamic stability was studied. Additionally, non-covalent interactions (NCI), frontier molecular orbitals (FMO), density of states (DOS), were investigated for providing further evidence of nitrobenzene sensing and its interaction with sensor. Natural bond orbital (NBO) analysis was carried out for charge transfer studies. Quantum theory of atom in molecule (QTAIM) and SAPT0 studies provided information about interaction points and binding energy. Additionally, IPA was investigated for NB sensing in real water samples, and its effective participation in solid state on-site detection as well as in solution phase was brought to light along with logic gate construction.

Triazine based fluorescent sensor for sequential detection of Hg2+ and L-Cysteine in real samples and application in logic Gate: A combination of Extensive experimental and theoretical analysis.

Triazine based fluorescent sensor TBT was rationally designed and synthesized to achieve sequential detection of Hg2+ and L-cysteine based on the presence of sulfur moiety and suitable cavity in the molecule. Sensor TBT exhibited excellent sensing potential for the selective detection of Hg2+ ions and L-cysteine (Cys) in real samples. Upon addition of Hg2+ to sensor TBT, enhancement in emission intensity of sensor TBT was observed which was accredited to the presence of sulfur moiety and size of cavity in the sensor. Upon interaction with Hg2+ blockage of intramolecular charge transfer (ICT) along with chelation-enhanced fluorescence (CHEF) resulted in the increase in fluorescence emission intensity of sensor TBT. Further, TBT-Hg2+ complex was employed for the selective detection of Cys through fluorescence quenching mechanism. This was attributed to the significantly stronger interaction of Cys with Hg2+, which resulted in the formation of Cys-Hg2+ complex and subsequently sensor TBT was released from TBT-Hg2+ complex. The nature of interaction between TBT-Hg2+ and Cys-Hg2+ complex was evaluated through 1H NMR titration experimentations. Extensive DFT studies were also carried out which include thermodynamic stability, frontier molecular orbitals (FMO), density of states (DOS), non-covalent interaction (NCI), quantum theory of atom in molecule (QTAIM), electron density differences (EDD) and natural bond orbital (NBO) analyses. All the studies supported the non-covalent type of interaction between analytes and sensor TBT. The limit of detection for Hg2+ ions was found to be as low as 61.9 nM. Sensor TBT was also employed for the quantitative detection of Hg2+ and Cys in real samples. Additionally, logic gate was fabricated by using sequential detection strategy.

New fluorescent probe for sensing of mefenamic acid in aqueous medium: An integrated experimental and theoretical analysis.

Abnormal levels of mefenamic acid (MFA) in living organisms can result in hepatic necrosis, liver, and gastrointestinal diseases. Therefore, development of accurate and effective method for detection of MFA is of great significance for the protection of public health. Herein, we designed a stilbene based sensor ECO for the sensitive and selective detection of mefenamic acid by employing fluorescence spectroscopy for the first time. The developed sensor ECO displayed fluorescence turn-off response towards MFA based on PET (photoinduced electron transfer) and hydrogen bonding. The sensing mechanism of MFA was investigated through 1H NMR titration experiment and density functional theory (DFT) calculations. The presence of non-covalent interaction was confirmed through spectroscopic analysis and was further supported by non-covalent interaction (NCI) analysis and Bader's quantum theory of atoms in molecules (QTAIM) analysis. Additionally, the sensor ECO coated test strips were fabricated for on-site detection of mefenamic acid. Furthermore, the practical applicability of sensor ECO to detect MFA was also explored in human blood and artificial urine samples.

Theoretical and experimental studies on mechanochromic triphenylamine based fluorescent "ON-OFF-ON" sensor for sequential detection of Fe3+ and deferasirox.

A novel triphenylamine (TPA) based sensor TTU was rationally designed and synthesized that exhibited reversible mechanochromic and aggregation induced emission enhancement (AIEE) properties. The AIEE active sensor was employed for fluorometric detection of Fe3+ in aqueous medium, with distinguished selectivity. The sensor showed a highly selective quenching response towards Fe3+ that is ascribed to complex formation with paramagnetic Fe3+. Subsequently, TTU-Fe3+ complex acted as a fluorescence sensor for the detection of deferasirox (DFX). The subsequent addition of DFX to TTU-Fe3+ complex led to the recovery of fluorescence emission intensity of sensor TTU that was attributed to the displacement of Fe3+ by DFX and release of sensor TTU. The proposed sensing mechanisms for Fe3+ and DFX was confirmed through 1H NMR titration experiment and DFT calculations. Frontier molecular orbitals (FMO), density of states (DOS), natural bond orbital (NBO), non-covalent interaction (NCI) and electron density difference (EDD) analysis were performed using DFT calculations to support the experimental results. Moreover, sensor TTU displayed colorimetric detection of Fe3+. Further, the sensor was employed for the detection of Fe3+ and DFX in real water samples. Finally, logic gate was fabricated by using sequential detection strategy.

AIEE active J-aggregates of naphthalimide based fluorescent probe for detection of Nitrobenzene: Combined experimental and theoretical approaches for Non-covalent interaction analysis.

A new naphthalimide-based fluorescent probe NS with exceptional J-aggregates based aggregation-induced emission enhancement (AIEE) properties was rationally synthesized through a single-step imidation reaction. Probe NS exhibited excellent AIEE properties in aqueous media through the formation of J-aggregates with remarkable red-shift. The AIEE active probe NS was used for selective and sensitive detection of nitrobenzene (NB) based on fluorescence quenching response. Formation of J-aggregates was assessed through fluorescence titration. These J-aggregates contributed significantly to produce favorable interaction between probe NS and NB. The highly selective fluorescence detection of NB was accredited to the adjustable smaller size of NB that can easily penetrate into interstitial spaces of probe molecules. Ability of sensor to detect NB in solid state was also accomplished through solid state fluorescence spectroscopy. Nature of interaction and sensitivity of probe NS for NB has also been investigated through 1H NMR titration and density functional theory (DFT) including non-covalent interaction (NCI), quantum theory of atom in molecule (QTAIM), electron density differences (EDD), frontier molecular orbitals (FMO) and density of states (DOS) analysis. Advantageously, probe exhibited colorimetric and vapor phase detection of NB. Moreover, probe was quite sensitive for the trace detection of NB in real samples.