Synthesis of Fluorescent Pyrazoline Sensors as Versatile Tool for Zinc ion Detection: A Mini-Review.

Zinc ions are one of the 2nd most abundant mineral after iron and it is important for immune system, enzymatic catalysis, DNA synthesis, and maintaining structural integrity in humans. But, monitoring the Zn levels in human body poses more challenges. This review paper investigates (paper from 2010 to 2023) the synthesis of pyrazoline derivatives by different methods, including conventional methods and green chemistry protocol. These Pyrazoline derivatives highlighted for their potential application as chemo-sensor for Zn2+ ions recognition. Pyrazoline compounds exhibit excellent sensitivity & selectivity and emitting blue-light with high quantum yields and electroluminescence, along with a superior limit of detection. These derivatives are stable bioactive molecule, with well-known diverse biological activities. This review not only gives valuable insights into the essential role of Zinc in human physiology but also provides a practical method for accurate Zinc detection in various samples. Which holds the potential for advancements in health diagnostics and environmental monitoring. Because of their significant biological application and selectivity as sensors, researchers have much more attention to prepare green environmentally-friendly pyrazoline derivatives.

Synthesis, Physicochemical and Third Order Nonlinear Optical Properties of Bis-Chalcone (BBDP) as Donor-pi Acceptor Chromophore in Organize Medium.

Bis-Chalcone (BBDP) has been prepared by condensation of N, N-dimethyl benzaldehyde and 1,1'-([1,1'-biphenyl]-4,4'-diyl) di (ethan-1-one), and structure of BBDP was characterized by Mass Spectra, 13C-NMR, 1H-NMR, and IR. Physicochemical properties including Dipole-moments, Stoke-Shifts, Oscillator-strength, dielectric constant and quantum-yields of fluorescence of BBDP were investigated by the emission and absorbances in different solvents. Compound (BBDP) displayed bathochromic shift upon increasing the solvent polarity (from n-Hexane to DMSO). Furthermore, we have exploited third-order nonlinear optical characteristics of the bisChalone were invigilated by the Z-scan techniques in Chloroform. The measurements were taken with a continuous-wave (CW) diode laser having a wavelength of 520 nm in CHCl3 solvent. The third-order nonlinear optical properties, such as the nonlinear refractive index (NLRI) n2, nonlinear absorption coefficient (NLAC) ß, and nonlinear susceptibility χ(3), were measured at various solution concentrations and laser powers. The obtained values of n2, ß, and χ(3) were estimated to be high, of the order of 10-7(cm2/W), 10-3 (cm/W), and 10-6 (esu), respectively. As a result, bis-chalcone (BBDP) is considered as a promising candidate for applications in nonlinear optical (NLO) devices and optical limiting (OL).

Ultrasound-Assisted Synthesis of Chalcone: A Highly Sensitive and Selective Fluorescent Chemosensor for the Detection of Fe3+ in Aqueous Media.

The chalcone compound DHPO was synthesized through a chemical reaction between 1-(2-hydroxyphenyl)-ethanone and 3,4-dimethoxy benzaldehyde under ultrasound irradiation. The interaction between the DHPO compound and several metal ions was studied using fluorescence behavior, revealing that the chalcone function as a "turn on and turn off" switch fluorescent sensor, for selectively and sensitively detecting Fe3+ ions. The process of fluorescence quenching and complexation of DHPO with Fe3+ ion was further studied using methods such as Benesi-Hildebrand, Stern-Volmer plot, and job plot.

Physicochemical parameters and modes of interaction associated with the micelle formation of a mixture of tetradecyltrimethylammonium bromide and cefixime trihydrate: effects of hydrotropes and temperature.

The interaction between an antibiotic drug (cefixime trihydrate (CMT)) and a cationic surfactant (tetradecyltrimethylammonium bromide (TTAB)) was examined in the presence of both ionic and non-ionic hydrotropes (HTs) over the temperature range of 300.55 to 320.55 K. The values of the critical micelle concentration (CMC) of the TTAB + CMT mixture were experienced to have dwindled with an enhancement of the concentrations of resorcinol (ReSC), sodium benzoate (NaBz), sodium salicylate (NaS), while for the same system, a monotonically augmentation of CMC was observed in aq. 4-aminobenzoic acid (PABA) solution. A gradual increase in CMC, as a function of temperature, was also observed. The values of the degree of counterion binding (ß) for the TTAB + CMT mixture were experienced to be influenced by the concentrations of ReSC/NaBz/NaS/PABA and a change in temperature. The micellization process of TTAB + CMT was observed to be spontaneous (negative standard Gibbs free energy change (ΔG0m)) at all conditions studied. Also, the values of standard enthalpy change (ΔH0m) and entropy change (ΔS0m) were found negative and positive, respectively (with a few exceptions), for the test cases indicating an exothermic and enthalpy-entropy directed micellization process. The recommended interaction forces between the components in the micellar system are electrostatic and hydrophobic interactions. In this study, the values of ΔC0m were negative in aqueous NaBz, ReSC, and PABA media, and positive in case of NaS. An excellent compensation scenario between the enthalpy and entropy for the CMT + TTAB mixed system in the investigated HTs solutions is well defined in the current work.

Site-Averaged Ab Initio Kinetics: Importance Learning for Multistep Reactions on Amorphous Supports.

Single-atom centers on amorphous supports include catalysts for polymerization, partial oxidation, metathesis, hydrogenolysis, and more. The disordered environment makes each site different, and the kinetics exponentially magnifies these differences to make ab initio site-averaged kinetics calculations extremely difficult. This work extends the importance learning algorithm for efficient and precise site-averaged kinetics estimates to ab initio calculations and multistep reaction mechanisms. Specifically, we calculate site-averaged proton transfer relaxation rates on an ensemble of cluster models representing Brønsted acid sites on silica-alumina. We include direct and water-assisted proton transfer pathways and simultaneously estimate the water adsorption and activation enthalpies for forward and backward proton transfers. We use density functional theory (DFT) to obtain a site-averaged rate, somewhat like a turnover frequency, for the proton transfer relaxation rate. Finally, we show that importance learning can provide orders-of-magnitude acceleration over standard sampling methods for site-averaged rate calculations in cases where the rate is dominated by a few highly active sites.

A Review on Schiff Base as a Versatile Fluorescent Chemo-sensors Tool for Detection of Cu2+ and Fe3+ Metal Ion.

Schiff bases as fluorescent Chemo-sensors fluorogenic cation sensors is scientifically exigent work. Recently Schiff bases derivatives gained more attention because of their structural variability. Donor and acceptor group joint with delocalized [Formula: see text]-orbital display excellent fluorescent properties due to intramolecular charge transfer (ICT). Schiff bases coordinate with the metal ions resulting in a small change of photophysical properties and typical sensing behavior hypochromic/hyperchromic or hypsochromic/bathochromic shift. In this review, we endeavored to converge the beforehand reported Schiff baes-derived sensors and investigated the probes' design, synthesis, ON/OFF & OFF/ON Fe 3+ and Cu2+ metal ion sensing mechanism, and practical application. This review focuses on the synthesis of Schiff baes as fluorescent Chemosensor for investigation of Fe and Cu metal ions during the period of over the two past decade (2003-2022). We anticipate that this review will provide a fundamental framework for researchers to further investigate the topic of Schiff-based sensors for metal ion detection.

A novel polymerase ß inhibitor from phage displayed peptide library augments the anti-tumour effects of temozolomide on colorectal cancer.

The therapeutic efficacy of TMZ, a common used drug for chemotherapy, is limited by the resistance from colorectal cancer cells. Base excision repair (BER) pathway has been identified as one of the reasons for drug resistance. By blocking Polß-dependent BER (Base Excision Repair) pathway, the efficacy of TMZ treatment can be improved greatly. Several Polß inhibitors that have been identified could not become approved drugs due to lack of potency or specificity. To find therapeutic candidates with exquisite specificity and high affinity to Polß, phage display technology was used in the current research. We screened out a candidate Polß inhibitor, 10 D, that can inhibit the activity of Polßand SP-BER (Short-Patch Base excision Repair) pathway. Co-treatment with 10 D enhanced the sensitivity of colorectal cancer (CRC) cells to TMZ both in vitro and in vivo. Our data suggested that the novel Polß inhibitor we identified can improve TMZ efficacy and optimize CRC chemotherapy.

Multi-step Synthesis, Characterization and Photophysical Investigation of Novel Biologically Active Heterocyclic Chalcone (AECO).

Novel alkylated heterocyclic chalcone (E)-1-(2-(allyloxy)phenyl)-3-(9-ethyl-9H-carbazol-3-yl)prop-2-en-1-one (AECO) with extended π-bond was prepared by the multi-steps synthesis. The structure of the AECO was established by the spectroscopic technics and purity of the compound was confirmed by the elemental analysis. Physicochemical parameters of the AECO such as molar absorption coefficient, transition dipole moments, stokes shift, oscillator strength and fluorescence quantum yield were calculated in ten various solvents on the basis of polarity of the solvents to see the effect of the solvent with AECO. Interaction of the AECO chromophore with cationic CTAB and anionic SDS surfactants were determined by using the fluorescence spectroscopy techniques. The intensity of the florescence spectrum increase with increasing the concentrations of surfactants. This suggests that strong interaction occurs between AECO with surfactants and this interaction arise from electrostatic forces. So, AECO chromophore could be used as analysis to define the Critical Micelle Concentration (CMC) of the surfactants. In addition the in-vitro antibacterial active of novel heterocyclic chalcone agents four bacteria's strain were evaluated and result showed AECO is beater antibacterial agent against Gram-Negative Bacteria (E. coli and S. flexneri) as compare to the Gram Negative Bacteria with respected to the standard drug Tetracycline.

Microwave assisted one-pot synthesis, photophysical and physicochemical studies of novel biologically active heterocyclic Donor (D)-π-Acceptor (A) chromophore.

A donor-π-acceptor (D-π-A) chromophore, 2-amino-4-(9-ethyl-9H-carbazol-3-yl)-8-methoxy-5,6-dihydrobenzo[h]quinoline-3-carbonitrile (AEDQ) was synthesized from the condensation of 6-methoxy-3,4-dihydronaphthalen-1(2H)-one, 9-ethyl-9H-carbazole-3-carbaldehyde, malononitrile and NH4OAc in ethanol. Spectroscopic techniques and elemental analysis were employed to establish the structure of AEDQ. Photophysical parameters and fluorescence quantum yield were calculated in the different polarity solvents to evaluate the interactions of the solvent with AEDQ chromophore. Further, the interaction of the AEDQ with cationic and anionic surfactants (CTAB, SDS) were also evaluated by using fluorescence spectroscopy techniques. The intensity of the fluorescence spectrum increased as the concentration of surfactants increased, suggesting that strong interaction occurs between AEDQ with surfactants, and this interaction arises from electrostatic forces. As a result, the AEDQ chromophore could be used to determine the CMC of surfactants. The disc diffusion and minimal inhibitory concentration (MIC) technique were used to test in-vitro antibacterial activity against Gram +ve and Gram -ve bacteria, and the results are compared with the standard drug, tetracycline. AEDQ also showed good ADMET, pharmacokinetics and drug-likeness properties, which are desirable for a good drug candidate. The molecule also fits well in the DNA gyrase A active pocket site with the binding free energy of -17.92 kcal/mol, which testifies its good antibacterial activity.

Importance learning estimator for the site-averaged turnover frequency of a disordered solid catalyst.

For disordered catalysts such as atomically dispersed "single-atom" metals on amorphous silica, the active sites inherit different properties from their quenched-disordered local environments. The observed kinetics are site-averages, typically dominated by a small fraction of highly active sites. Standard sampling methods require expensive ab initio calculations at an intractable number of sites to converge on the site-averaged kinetics. We present a new method that efficiently estimates the site-averaged turnover frequency (TOF). The new estimator uses the same importance learning algorithm [Vandervelden et al., React. Chem. Eng. 5, 77 (2020)] that we previously used to compute the site-averaged activation energy. We demonstrate the method by computing the site-averaged TOF for a simple disordered lattice model of an amorphous catalyst. The results show that with the importance learning algorithm, the site-averaged TOF and activation energy can now be obtained concurrently with orders of magnitude reduction in required ab initio calculations.

How fluxional reactants limit the accuracy/efficiency of infrequent metadynamics.

In an infrequent metadynamics (iMetaD) simulation, a well-tempered metadynamics bias accumulates in the reactant basin, accelerating escapes to the product state. Like the earlier hyperdynamics strategy, iMetaD enables estimates of the unbiased escape rates. However, iMetaD applies the bias to visited locations in a collective variable (CV) space, not to the more specific visited locations in a full configuration space as done in hyperdynamics. This difference makes rate estimates from iMetaD sensitive to the choice of CVs, to parameters that control the bias deposition rate, and to the preparation of the initial state within the reactant basin. This paper uses an extremely simple discrete state model to illustrate complications that can arise in systems that exhibit fluxional transitions between sub-basins of the reactant state. Specifically, we show how the reactant-to-product escape time and relaxation times within the reactant basin(s) impose bounds on the admissible parameter choices for an iMetaD calculation. Predictions from the discrete state model are validated by iMetaD simulations on a corresponding two-dimensional potential energy surface.

Synthesis of Nitrogen Containing Chalcone: A Highly Sensitive and Selective Fluorescent Chemosensor for the Fe3+ Metal Ion in Aqueous Media.

Title compound (PTPO) was synthesized by the reaction of 2-acetyl pyridine with 3,4,5-trimethoxy benzaldehyde. The structure of the compound has been confirmed by spectroscopic techniques. Interaction of chalcone with different metal cations was analyzed based on the fluorescence behavior. Results show that chalcone act as on-off switching fluorescent chemosensor for selective and sensitive detection iron metal ion. Mechanism of quenching and complexation were resolute by Benesi-Hildebrand, Stern-Volmer plot and Job-plot.

N-Trifluoroacetylated pyrazolines: Synthesis, characterization and antimicrobial studies.

A series of N-trifluoroacetyl-2-pyrazolines have been synthesized via cyclization of chalcones in the presence of trifluoroacetic acid and hydrazine as a base. The method used for the preparation of pyrazolines was found to be an efficient one as all of the compounds were obtained in good yield (up to 79%). Various spectroscopic techniques established the structures and additionally corroborated the compounds 2a and 2e by single crystal X-ray. Newly synthesized pyrazolines were investigated for their potential as antimicrobial agents. Compound 2a displayed promising antimicrobial activity against pathogenic Escherichia coli and Pseudomonas aeruginosa. Furthermore, the mechanism of the antimicrobial activity of 2a was demonstrated with the help of scanning electron microscopy (SEM), which revealed complete damage of the bacterial cell membrane, providing dead cell debris in the milieu. The minimum inhibitory concentration (MIC) observed was 79 and 90 µM against E. coli and P. aeruginosa, respectively. Hence, these compounds might be significantly useful in antimicrobial drug development.

Synthesis and evaluation of Quinoline-3-carbonitrile derivatives as potential antibacterial agents.

New quinoline-3-carbonitrile derivatives were synthesized and evaluated for their potential antibacterial behavior. Compounds were obtained by a one-pot multicomponent reaction of appropriate aldehyde, ethyl cyanoacetate, 6-methoxy-1,2,3,4-tetrahydro-naphthalin-1-one and ammonium acetate. Structures were established by different physical and spectroscopic techniques. The molecular geometry, vibration frequencies, HOMO-LUMO energy gap, molecular hardness (g), ionization energy (IE), electron affinity (EA), and total energy of these compounds was assessed by DFT studies, employing DFT/RB3LYP method. Preliminary antibacterial studies using both Gram-positive and Gram-negative bacterial strains and cytotoxicity studies on mammalian cells revealed their promising antibacterial activity, without causing any severe host toxicity. All the compounds (QD1-QD5) in this study obeyed the 'Lipinski's Rule of Five' with logP values <5 and HBA <10, hydrogen bond donor's <5. The most active compound QD4 showed good interaction with the target DNA gyrase; target enzyme for quinoline class of antibiotics, which reveals its probable mechanism of action. Results of all these studies establish these compounds as important scaffolds with broad-spectrum antibacterial activity with no off-target toxicity. Having lower band gap energy of 3.40 eV and a low lying LUMO for compound QD4, this compound may be a valuable starting point for the development of quinoline-3-carbonitrile based broad-spectrum antibacterial agents.

Multi-step synthesis, spectroscopic studies of biological active steroidal thiosemicarbazones and their palladium (II) complex as macromolecules.

Steroidal Pd (II) metal complexes were synthesized by the reaction of steroidal thiosemicarbazones with [Pd (DMSO)2 Cl2]. The steroidal thiosemicarbazones coordinate to palladium through the azomethine nitrogen and thionic sulfur. The thiosemicarbazone derivatives were obtained by the reaction of thiosemicarbazide with steroidal ketones. The identity of steroidal thiosemicarbazones and their Pd(II) metal complexes were elucidated by IR, 1H, 13C NMR, FAB mass spectroscopic methods, elemental analysis and TGA analysis. The antibacterial activity of these compounds were tested in vitro by disk diffusion assay against two Gram-positive and two Gram-negative bacteria. The results showed that the Pd(II) complexes are better growth inhibitors than steroidal thiosemicarbazones of both types of the bacteria (gram-positive and gram-negative). The compound 2a {[Pd(C35H54N3SCl)Cl2]} is a as good as antibacterial agent as compared to amoxicillin.

Synthesis and spectroscopic studies of Ru(II) complexes of steroidal thiosemicarbazones by multi step reaction: As anti-bacterial agents.

Ru(II) steroidal metal complexes were synthesized by the reaction of dichlorodicarbonyl ruthenium(II) [Ru(CO)2Cl2]n with Steroidal thiosemicarbazones. Coordination via the thionic sulfur and the azomethine nitrogen atom of the thiosemicarbazone to the Ru(II) metal. Steroidal thiosemicarbazone derivatives were obtained by the thiosemicarbazide with steroidal ketones. Structures of the steroidal thiosemicarbazone and their metal complexes were confirmed by the FT-IR, 1H NMR, 13C NMR, Fab-Mass spectroscopy and elemental analysis. The antibacterial activity of these compounds were first tested in vitro by the disk diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration (MIC) was determined. The results showed that steroidal Ru(II) complexes are better inhibit growth as compared to steroidal thiosemicarbazones of both types of the bacteria (gram-positive and gram-negative).

Optical and Photophysical Investigation of (2E)-1-(2,5-Dimethylfuran-3-Yl)-3-(9-Ethyl-9H-Carbazol-3-Yl)Prop-2-en-1-One (DEPO) by Spectrofluorometer in Organized Medium.

(2E)-1-(2,5-dimethylfuran-3-yl)-3-(9-ethyl-9H-carbazol-3-yl)prop-2-en-1-one (DEPO) was prepared by the reaction of 9-ethyl-9H-carbazole-3-carbaldehyde with 1-(2,5-dimethylfuran-3-yl)ethanone under microwave irradiation. The structure of DEPO was established experimentally by EI-MS, FT-IR, 1H and 13C NMR spectral studies. Electronic absorption and emission spectra of DEPO were studied in different solvents on the basis of polarities, and the obtain data were used to determine the solvatochromic properties such as extinction coefficient, oscillator strength, transition dipole moment, stokes shift, fluorescence quantum yield and photochemical quantum yield. Photochemical quantum yield (Φ c ) of DEPO dye was determined in different solvent. The dye comparatively photostable in DMSO but undergoes photodecomposition in chloro methane solvents. The DEPO dye may be use as probe or quencher to determine critical micelle concentration (CMC) of cetyltri methyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS).

Green Synthesis, Spectrofluorometric Characterization and Antibacterial Activity of Heterocyclic Compound from Chalcone on the Basis of in Vitro and Quantum Chemistry Calculation.

2-amino-4-(4-bromophenyl)-8-methoxy-5,6-dihydrobenzo[h]quinoline-3-carbonitrile (ABDC) was synthesized by the reaction of (2E)-2-(4 bromobenzylidene) - 6 -methoxy-3,4-dihydronaphthalen-1(2H)-one (Chalcone) with malononitrile and ammonium acetate under microwave irradiation. Chalcone was synthesised by the reaction 4-bromobenzaldehyd, 6-methoxy-1,2,3,4-tetrahydro-naphthalin-1-one under the same condition. Structure of ABDC was conformed by 1H and 13C NMR, FT-IR, EI-MS spectral studies and elemental analysis. The electronic absorption and fluorescence spectra of ABDC have been studied in solvents of different polarities, and the data were used to study the solvatochromic properties such as excitation coefficient, stokes shift, oscillator strength, transition dipole moment and fluorescence quantum yield. The absorption maximum and fluorescence emission maximum was observed red shift when increase solvent polarity n-Hexane to DMSO. ABDC undergoes solubilization in different micelles and may be used as a probe and quencher to determine the critical micelle concentration (CMC) of CTAB and SDS. The anti-bacterial activity of chalcone and its cyclized product ABDC was tested in vitro by the disk diffusion assay against two Gram-positive and two Gram-negative bacteria was determined with the reference of standard drug Tetracycline. Results showed that the ABDC is better anti-bacterial agent as compared to chalcone. The anti-bacterial activity was further supported by the quantum chemistry calculation.

Microwave Assisted Synthesis, Optical Properties and Physicochemical Investigations on the Powerful Fluorophore: Donor (D) -π-Acceptor (A) Chalcone.

(2E)-3-[4-(dimethylamino)phenyl]-1-(2-hydroxyphenyl)prop-2-en-1-one (DPHP) was synthesized by the reaction 4(dimethylamino) benzaldehyde with 1-(2-hydroxyphenyl) ethanone under microwave irradiation. Structure of DPHP was conformed by 1H and 13C NMR, FT-IR, EI-MS spectral studies and elemental analysis. The electronic absorption and fluorescence spectra of DPHP have been studied in solvents of different polarities, and the data were used to study the solvatochromic properties such as extinction coefficient, stokes shift, oscillator strength, transition dipole moment, fluorescence quantum yield and photochemical quantum yield. The absorption maximum and fluorescence emission maximum was observed red shift when increase solvent polarity n-Hexane to DMF. DPHP undergoes solubilization in different micelles and may be used as a probe and quencher to determine the critical micelle concentration (CMC) of CTAB and SDS.