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D–π–A dye composed of pyrene and thiophene units was synthesized and characterized using elemental, FT-IR, and mass analyses. The solvatochromic response was investigated in different solvents of various polarities. Additionally, the inclusion characteristic of the investigated dye was studied in different organized assemblies of three surfactants. The spectral changes suggested that the dye would be useful to study the critical micelle concentrations of the studied assemblies systems. Furthermore, the absorption and emission spectra are sensitive towards H+, Co2+, Ni2+, Cd2+, Pb2+, and Zn2+ ions owing to acido- and metallo-chromic behaviors. These results suggest that the investigated dye would be potential candidate for polarity sensors, probe to characterize microenviromental polarity of the surfactants, and sensor for metal ions and H+ proton.

Herein, we report on developing a facile synthetic route for reusable nanocatalysts based on a combination of the supermagnetic properties of magnetite with the unique optical and catalytic properties of noble metal hybrid nanomaterials. We compare two different synthetic methods, to find out which is best from synthetic and application points of view, for the synthesis of Fe3O4 and Fe3O4@M (M = Ag or Au) core–shell hybrid nanostructures. The two different single-step synthetic methods are: thermal decomposition and hydrothermal. The structural, morphological and magnetic properties of the obtained Fe3O4 and Fe3O4@M nanoparticles were characterized by various techniques. XRD of the Fe3O4 nanoparticles exhibited sharp and strong diffraction peaks, confirming the highly crystalline structure of the Fe3O4 particles synthesized by the hydrothermal method, while broad and weak peaks were observed on using the thermal decomposition method. Both Fe3O4@Ag and Fe3O4@Au core–shells obtained by the hydrothermal method showed the reflection planes of Fe3O4 and additional planes of Ag or Au. But on the formation of Fe3O4@Ag/Au by the thermal decomposition method the peak for Fe3O4 disappeared and only the diffraction peaks of Ag or Au appeared. According to TEM analysis there was a broad particle-size distribution, random near-spherical shapes and slight particle agglomeration for Fe3O4 synthesized by the thermal decomposition method. However, there was a moderate size distribution, spherical shapes and well-dispersed particles without large aggregations for the hydrothermal method. TEM images of the synthesized nanoparticles by the two methods used showed a pronounced difference in both size and morphological shape. The catalytic performance of the synthesized nanoparticles was examined for the reduction of Congo red dye in the presence of NaBH4. The Fe3O4 nanocatalyst maintained its catalytic activity for only one cycle. In the cases of Fe3O4@Au and Fe3O4@Ag, the catalytic activity was conserved for four and ten successive cycles, respectively. Based on the obtained results, it was concluded that the hydrothermal synthesis of Fe3O4, Fe3O4@Ag and Fe3O4@Au nanostructures is highly recommended due to their selectivity and merits.

D–π–A chalcone composed of pyrene and thiophene units wassynthesized and characterized. The solvatochromic response wasinvestigated in different solvents of various polarities. Additionally, theinclusion characteristic of the investigated dye was studied in differentorganized assemblies of three surfactants. The spectral changessuggested the chalcone would be useful to study the critical micelleconcentrations of the studied assemblies systems. Furthermore, theabsorption and emission spectra are sensitive towards H+, Co2+, Ni2+,Cd2+, Pb2+, and Zn2+ owing to acido- and metallo-chromic behaviors.These results suggest that the investigated chalcone would be potentialcandidate for polarity sensors, probes to characterize microenviromentalpolarity of the surfactants, and sensors for metal ions and H+ proton.

Herein, the effects of media on the fluorescence characteristics (mainly quantum yield, lifetime and radiationless deactivation rate of the excited singlet state) of phenylene-1,4-ethylene-bis-(2-quinoxaline) laser dye, BQxVB have been reported. Also, the sensitivity of the dye to the proton has been tested by studying the effect of changing the acidic properties of the medium. As with polarity, the acidity of solution provokes spectral changes. As the acidity of the medium increases (using H2SO4 solutions), the pale yellow color of BQxVB changes to orange then violet and eventually to deep blue in concentrated acid solutions. The effect of metallic and bimetallic nanoparticles on the spectral behavior of BQxVB dye has been investigated. Additionally, the binding of the dye by β-cyclodextrin was investigated. The capped and binding of the dye with CT-DNA were visualized based on the spectral studies. Finally, a molecular docking analysis was carried out on five chosen proteins, which are largely responsible for the formation of CT-DNA, 4ASD-transferase, 3UW9 protein binding, 3DDC–hydrolase/apoptosis, 3L8-transferase/CT-DNA, and 4ICH-transcription. Based on the results, it has been clearly shown that BQxVB shows better docking with the 4ASD-transferase protein than the other selected proteins, with an estimated binding Gibbs energy of − 50.45 kJ·mol−1, a total intermolecular energy of − 55.09 kJ·mol−1, an inhibition constant of 1.48 nmol·dm−3, and a binding efficiency of 80%.

We have reported fast and simple synthesis of electrochemically reduced graphene oxide nanosheets (ErGO NSs)-embedded-palladium nanoparticles (Pd-E-ErGO) hybrids on nickel (Ni) sheet for high performance electrochemical supercapacitors (SCs) electrode. The Pd-E-ErGO hybrids material was successfully prepared by facile and one-pot in-situ electrochemical reduction and deposition using water as solvent in which palladium nanoparticles (Pd NPs) were uniformly embedded inside 2D-nanosheets of ErGO. During electrochemical reduction, graphene oxide nanosheets were reduced into ErGO NSs and PdCl2 ionized to form Pd2+ which attracted to the negative oxygen containing functional groups of ErGO NSs then reduced to form Pd NPs which embedded completely between ErGO NSs structure. The surface/structural morphology of Pd-E-ErGO hybrids was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The proportions of elements present in hybrids were determined by EDS and thermogravimetric analysis (TGA). As an application, the synthesized Pd-E-ErGO hybrids revealed enhanced electrochemical performance as high specific capacitance with excellent cycling stability which was very significant for electrochemical SCs. The Pd-E-ErGO hybrids electrode fulfills an approving specific capacitance value of 1524.7 F/g at a scan rate of 20 mV/s and improved cycling stability of 92.1% capacitance retention after 2000 cycles in the three-electrode setup. The electrochemical synthesis of Pd-embedded-graphene derivatives structure as well as improved electrochemical performance for SCs opens up a new idea to prepare electrode materials.

Herein, we report on developing a facile synthetic route for reusable nanocatalysts based on a combination of the supermagnetic properties of magnetite with the unique optical and catalytic properties of noble metal hybrid nanomaterials. We compare two different synthetic methods, to find out which is best from synthetic and application points of view, for the synthesis of Fe

Toward the goal of detecting toxic elements and removing them from drinking water, we report herein the utilization of Acid Red 94 (AR94) in sensing the hazardous metal ions in water. Among the various examined metal ions (Ag+, Pb2+, K+, Mn2+, Zn2+, La3+, Hg2+, Ca2+, Cd2+, Co2+, and Ni2+), the UV-visible absorption spectra showed high selectivity and sensitivity for toxic silver and lead metal ions in an aqueous solution. The observed absorption spectral changes and the rapid color changes confirm complex formation between AR94 and both Ag+ and Pb2+ metal ions. The emission measurements showed the significant fluorescence quenching of the singlet excited state of AR94 in the presence of Ag+ and Pb2+ metal ions suggesting the formation of an irradiative dye–metal complex under the prevailing experimental conditions. In order to remove the accumulated complexes of AR94 with silver metal ions, safe and harmless mesoporous titanium dioxide was utilized efficiently in removing the complexes with adsorption capacities of 91% at 30 minutes. These findings suggest a simple, fast and efficient method for both detecting silver in water, and removing the formed AR94–metal complexes in water. In addition, AR94 is shown to be a good sensor for the presence of Ag and Pb nanoparticles, NPs, in aqueous solution. The absorption and emission spectra of AR94 showed significant changes that may be rationalized by the strong electromagnetic coupling induced by NPs plasmonic effects. These findings render AR94 a sensitive and selective sensor and a visual indicator for the qualitative and quantitative detection of silver ions, lead ions and their nanoparticles.

Novel naked eye optical chemosensor containing thiazole ring, namely; (2E,4E)-5-(4-(dimethylylamino)phenyl)-1-(thiazol-2-yl)penta-2,4-dien-1-one, DMAPTP was developed. The solvatochromic response was explored in different solvents of various polarities. The dipole moments in the ground (µg) and excited (µe) states were determined. The large excited state dipole moment demonstrates the excited state's stability in polar solvents. In an ethanolic solution, the sensing response and selectivity of the investigated chemosensor to various metal ions such as Na+, K+, Ca2+, Ba2+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Al3+, Hg2+, and Pb2+ were evaluated. The spectral changes suggest that DMAPTP is strongly complexed with the metal ions used. The ground and excited state binding constants, as well as the quenching constants, have been determined. The mechanism of fluorescence quenching was identified as static quenching due to the formation of a non-fluorescent ground state complex using the Stern-Volmer plot. DMAPTP can also be used as a powerful chemosensor, identifying all of the metal ions studied with high sensitivity and selectivity for Fe3+ ions. DMAPTP can serve as a Turn-on-off-on chemosensor, as well as a metallochromic predictor in complexometric titration. This is indicated by the ability of EDTA to decompose the formed complex with the formation of the stable metal-EDTA complex, which leads to fluorescence recovery. The analytical parameters, such as selectivity, sensitivity, and detection limit, were chosen. The fluorescence imaging experiments in living cells demonstrated the biological chemosensing applications of DMAPTP to Fe3+ ions. Furthermore, weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy techniques were used to investigate DMAPTP as a corrosion inhibitor for carbon steel in 1.0 M HCl. The collected data reveal that as DMAPTP concentrations increased, its inhibition performance increased as well. On the basis of strong adsorption of inhibitor molecules on the surface of carbon steel and the formation of large protection films, the inhibition efficiencies were determined.

Donor–Acceptor (D–π–A) chalcone containing phenanthrene and keto-thiophenly moieties, abbreviated as PhTPO, was synthesized and characterized. The solvatochromic effect was investigated in different solvents of various polarities. The absorption and fluorescence spectra have shown bathochromic shifts from non-polar to polar solvents due to intramolecular charge transfer interactions. The fluorescence characteristics (fluorescence intensity, fluorescence maxima, and energy) of PhTPO are highly sensitive to the polarity of the solvents compared to the corresponding absorption spectra. In addition, the inclusion characteristic of PhTPO in different organized assemblies was studied. The spectral changes suggested that PhTPO would be useful to study the microenviromental polarity and evaluation of critical micelle concentrations of the studied surfactants. Reversible acidochromic behavior was observed after addition of H2SO4/NaOH with a significant color change. Further, the optical sensing response towards H+, Co2+, Ni2+, Pb2+ and Cd2+ ions was investigated. Also, it responds well to the tested metal ions as reflected from the changes in both the absorption and emission spectra upon adding different concentrations of the metal salts. The solid complexes of PhTPO with Co2+, Ni2+, Pb2+ and Cd2+ were then synthesized and characterized. Depending on the magnetic moments results, the geometric structures were found to be octahedral and tetrahedral for paramagnetic Co2+, and Ni2+ complexes, respectively, while they are diamagnetic for Pb2+ and Cd2+ complexes. Moreover, the geometry of PhTPO and its complexes were confirmed by the density functional theory (DFT) using DMOL3 program. The binding affinity towards the epidermal growth factor receptor (EGFR) protein was also investigated by the Molecular Operating Environment (MOE) software. The anticancer activity was then evaluated against four different cell lines using MTT assay. The results suggest that the investigated PhTPO would be potential candidate for solvents polarity sensors, as a probe to characterize critical micelle concentrations of surfactants, and sensor for the studied metal ions and H+ proton. In addition, [PhTPO Ni2+] and [PhTPO Co2+] complexes are good candidate for further antitumor activities studies owing to their potent cytotoxic and anticancer activities compared to the Pb2+ and Cd2+ complexes.

Three novel chelates, [Ru(L)3]2H2O, C1, [NiL(H2O)3(AcO)]H2O, C2, and [CuL(H2O)(AcO)], C3, derived from 2-(2-hydroxy phenyl)-1-H –benzimidazole) HL, have been designed. The structures of the isolated compounds have been elucidated by elemental analysis, molar conductance, thermal analysis, spectral data (UV–Vis, mass spectra, IR, fluorescence), thermal analysis (TGA) and magnetic moment measurements. The IR spectral data ascertained that the HL compound acts as a monobasic bidentate ligand via the O and N atoms of the OH and C=N groups of the benzimidazole moiety, respectively. The spectral and magnetic measurements implied octahedral structures for C1 and C2 and square planar geometry for C3. The kinetic and thermodynamic parameters of the thermal decomposition stages have been evaluated. Molecular orbital calculations have been performed. The metallochromic behavior of the investigated free ligand was studied in the presence of Ru(III), Ni(II) and Cu(II) ions. The observed spectral changes indicated the ability of HL to act as potential optical sensor for probing these metal ions. Interaction of the investigated compounds with CT-DNA was studied via electronic absorption and emission spectroscopy, as well as ethidium bromide displacement. The results suggested that all compounds interact through intercalative mode. The binding behavior and binding constants have been evaluated and discussed. The CT-DNA-binding constants confirmed the strong intercalation between the investigated ligand and metal complexes with the CT-DNA, suggesting that the investigated compounds can be used as promising therapeutic drug. Finally, the antimicrobial activities of the metal complexes have been screened.

A number of new Cr(III), Mn(II), Cu(II) Zn(II) and Cd(II) chelates of (E)-3-(4-(dimethyl-amino)phenyl)-1-(pyridin-2-yl)prop-2-en-1-one were synthesized. The structures were elucidated by elemental and thermal analysis as well as spectral techniques (mass, IR, and electronic spectra) and magnetic measurements. The IR data suggested that the investigated chalcone acted as a bidentate ligand via the O and N atoms of the C O and C N groups, respectively. The spectral plus magnetic data revealed the formation of octahedral structures for all chelates while Cu(II) chelate has the square planar geometry. The kinetic and thermodynamic parameters of the thermal decomposition stages have been evaluated. Molecular orbital calculations have been performed to confirm the geometry of the isolated compounds. The in vitro antimicrobial activities of the chalcone and its metal chelates have been performed against some bacterial strains. The data indicated that all the metal chelates demonstrated a higher activity than the free chalcone. The anticancer activity of the mentioned metal chelates is evaluated against MCF7 cell. These compounds exhibited a moderate and weak activity against the tested cell line. The results were correlated with the experimental data.

In this work we report the synthesis of electrochemically deposited Ni(OH)2 nanoparticles on the surface of in-situ electrochemically reduced graphene oxide nanosheets (ErGO NSs) supported on 3D networked nickel foam (NF) to form Ni(OH)2-ErGO@NF as electrode materials for supercapacitor (SCs) application. The adopted three-electrode electrochemical system via a two-step process for the synthesis of Ni(OH)2-ErGO@NF was fast and cost effective. First, 2D nanosheets of ErGO were deposited on NF by potential square wave technique. Second, Ni(OH)2 nanoparticles were deposited on the surface of 2D nanosheets ErGO by potentiostat. The electrochemical behavior of the Ni(OH)2-ErGO@NF electrode was measured in 1 M KOH and revealed an impressive supercapacitive performance, with high specific capacitance of 3138 F/g at scan rate 20 mV/s. The synthesized Ni(OH)2-ErGO@NF exhibited excellent cyclic stability, with capacitance retention of 88.6% after 3000 cycles at a scan rate 50 mV/s. The enhanced electrochemical performance of SCs was attributed to the superior conductivity of ErGO NSs, which facilitated the transfer of charges and the diffusion of KOH electrolyte, making it is a promising candidate for SCs electrodes. This synthesis provides an appropriate approach for preparing other kinds of metal hydroxides with rGO for improved SCs electrode performance.

The fluorescence quenching of newly synthesized diarylethylenes by some aliphatic and aromatic amines has been carried out at room temperature in solvents of various polarities and viscosities including acetonitrile, methanol, ethanol, and cyclohexane using steady-state measurements. Additionally, the cyclic voltammetric behavior of the investigated diarylethylenes has been studied, in order to determine their reduction potentials, which are necessary for calculation the Gibbs energy change for the photoinduced, electron transfer (ET) reactions in diarylethylene–amine systems. No change in the shape of the fluorescence spectra was observed, except for diarylethylenes–N,N-dimethyl aniline pairs in cyclohexane at which an exciplex was observed. The quenching mechanism is due to the ET from the ground state amines to the excited diarylethylenes. Both linear and non-linear Stern–Volmer behaviors have been encountered. The observed k q values for different diarylethylenes–amine pairs do not correlate with the basicity (pK b) of the amines but decrease with increasing the oxidation potentials of the amines. The bimolecular quenching rate constants have been correlated with ∆G° values for the ET reactions according to the Marcus outer-sphere ET theory.

Nanosensors are one of the important applications of mesoporous materials used for toxic metal ions detection. Here, a rational strategy aimed at designing 2D and 3D nanosensors using SBA-15 and KIT-6 types of mesoporous silicates as probe carriers. A novel ligand of chalcone analogue namely, chalcone isothiocyanate, CITC has been synthesized. Covalent anchoring of CITC into mesoporous silicates was performed through two methods: (i) loading via the coupling agent (3-aminopropyl) trimethoxysilane (APS) into calcinated mesoporous silicates, (ii) alkaline loading into amino-functionalized mesoporous silicates. The obtained mesoporous silicates and their CITC anchored forms were characterized using different spectroscopic techniques. The results indicated the higher efficiency of KIT-6 and APS loading method than both SBA-15 and alkaline loading method. Therefore, a highly sensitive nanosensor used for toxic metal ions detection was successfully designed by the anchoring of CITC into KIT-6 via the more efficient APS method. Among of metal ions, the most widely toxins, Cd(II), Co(II) and Sb(III) were studied. The optical sensing of these metal ions was performed using electronic absorption and emission techniques. The absorption spectra increase gradually upon increasing the concentrations of the used metal ions, with significant color changes. Also, a great enhancement in the fluorescence intensity was observed upon adding these metal ions. The spectral changes can be rationalized in terms of the formation of [M(CITCs-KIT-6)n]2+ complexes. These results suggested that CITC/KIT-6 nanosensor is suitable for the on-line analysis and in situ detection of these toxic ions in potable and environmental water samples.

The photophysical behaviors of newly synthesized photochromic dyes have been investigated in different solvents of various polarities using steady-state absorption and emission techniques. It was found that, the absorption and emission spectra of these dyes depend on the ring size and the solvent polarity. The higher values of the dipole moments of the investigated dyes in the excited state than those in the ground state suggest that these dyes can serve as good candidate components of nonlinear optical materials. Additionally, the photoisomerization parameters (percentage of composition of cis isomers and quantum yields of photoisomerization) depend on the polarity and the viscosity of the used solvents as well as the ring size. The molecular motion that occurs in the isomerization process has facilitated the development of molecular devices. Finally, the halochromic behaviors of the investigated dyes promise them to act as acid-base indicators.

Mesoporous silicate, SBA-16 is one of the most promising supports for horseradish peroxidase. In this study, SBA-16 was synthesized, and the anchored HRP enzyme in the organized porous networks, SBA-16. The mesoporous material, SBA-16 and the anchored HRP enzyme were characterized by Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption isotherms, low-angle XRD and thermogravimetric analysis. The percentage of immobilized HRP was 57%. The enzyme affinity constant, Km values of soluble and immobilized enzyme were 5.27 and 3.9 mM for hydrogen peroxide and 12 and 10.4 mM for guiacol, respectively, indicating that the immobilized enzyme had more affinity to the substrate than free HRP. Also, the free and immobilized enzyme had pH and temperature optima at 5.6, and 40 °C, respectively. The free enzyme was stable at 40 °C but that for the immobilized enzyme was detected up to 60 °C. Reusability of immobilized enzyme was found to be 10 cycles; the immobilized enzyme can only retain 50% of its activity after 5 cycles. The results indicate the higher efficiency, stability, and reusability of the immobilized enzyme than free enzyme. The HRP immobilized to SBA-16 due to the large surface area, and narrow pore size distribution of SBA-16.

Here we report synthesis of mesoporous structure containing two different phases of Co(OH)2 by different routes. The β-Co(OH)2 film and mesoporous α-Co(OH)2 powder synthesized using electrochemical deposition and chemical reduction methods, respectively using lyotropic liquid crystal (LLC) templates. These synthesized mesoporous β-Co(OH)2 film and α-Co(OH)2 powder were utilized as electrode materials for supercapacitors (SCs)application. The surface structure/morphology of these synthesized materials were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), wide/low-angle X-ray diffraction (XRD) and Raman spectroscopy. The as-synthesized mesoporous β-Co(OH)2 film and mesoporous α-Co(OH)2 powder contain particles size in the range of 270–300 nm and 70–90 nm, respectively. For application as electrode in SCs, mesoporous β-Co(OH)2 film on FTO reveals enhanced electrochemical performance as compared to mesoporous α-Co(OH)2 powder in 1 M KOH electrolyte as high specific capacitance with a significant tremendous long-term cyclic stability. The specific capacitance of mesoporous β-Co(OH)2 film was 605 F/g at scan rate 10 mV/s and superior cyclic stability as capacitance retention of 94.4% over 2000 cycles. Uniform and homogeneous Co(OH)2 nanoparticles inside film enhance the electrochemical performance for SCs due to easy penetration and access of KOH electrolyte inside mesoporous structure. The reported synthesis method provides a suitable and fast approach to synthesize other kind of metal hydroxide mesoporous structure for electrode purpose for different energy storage devices.

An “on–off–on” switchable optical chemosensor namely: 5-(4-dimethylamino-phenyl)-1-pyridin-2-yl-penta-2,4-dien-1-one, DMAC and its metal complexes were synthesized and characterized. The optical studies of DMAC were presented, and reveal several interesting points when different metal ions such as Co(II), Ni(II) and Cu(II) were added. The results showed that the absorption and emission spectra are very sensitive to the used metal ions. Detectable cation-induced effects were observed on adding different concentrations of the used metal ions to DMAC, with instantaneous color change. The origin of the color change was attributed to modulation of the intramolecular charge transfer of chemosensor DMAC upon effective coordination with the used metal ions through nitrogen atoms of pyridine moiety along with oxygen of carbonyl group. Furthermore, ethylene diamine tetraacetic acid (EDTA) can selectively turn on the absorption and emission spectra of DMAC complex induced by the used metal ions (“on–off–on” type sensor). The stability constants, K , have been determined and confirming the formation of 1:1 complexes between DMAC and the used metal ions. Solid Co(II), Ni(II) and Cu(II) complexes were synthesized and characterized by a set of chemical and spectroscopic measurements using elemental analysis, electrical conductance, mass spectra, magnetic susceptibility and spectral techniques (FT-IR, UV–vis, 1 H NMR). The structure of metal complexes has been also theoretically studied using molecular mechanics (MM + ). The structures obtained were minimized with a semi-empirical (PM3) method. The synthesized DMAC and its complexes were screened for their biological activities.

Fluorescent nanosensors are one of the most efficient techniques used for detection of toxic metal ions, based on ligand embedded into mesoporous materials. Here, novel ligands of chalcone isothiocyanate analogue namely; phenyl chalcone isothiocyanate (PCITC), naphthyl chalcone isothiocyanate (NCITC) and anthryl chalcone isothiocyanate (ACITC) were synthesized. Also, the 3D mesoporous silicate, KIT-6, was prepared through surfactant-template method. The design of fluorescent nanosensors was achieved by anchoring of CITCs into KIT-6 via the coupling agent (3-aminopropyl) triethoxysilane (APS). The obtained mesoporous silicate and CITCs anchored forms were characterized using different spectroscopic techniques. Among of metal ions, the most widely toxins, Pb(II), Cu(II) and Pd(II) were studied. Sensing of these metal ions was performed using steady-state absorption and emission techniques. A gradual increase in the absorption spectra was observed upon increasing the concentrations of the used metal ions ranging from 5 ppb to 1 ppm, with instantaneous color change. Also, a great enhancement in the fluorescence intensity was clearly observed, confirming the formation of [M(CITCs-KIT-6)n]2+ complexes. The calculated binding constants show the high efficiency of PCITC-KIT-6 nanosensor in binding and detection of these metal ions. Moreover, Pb(II) is the strongest binded metal ion with the investigated fluorescent nanosensors. Therefore, CITCs fluorescent nanosensors are suitable for the on-line analysis and remote determination of these toxic metal ions, specially Pb(II), at low concentration levels.

The absorption and fluorescence spectral characteristics of some symmetrical ketocyanine dyes have been investigated in different solvents of various polarities using steady-state absorption and emission spectroscopic techniques. The absorption spectral features are less sensitive to the solvent characteristics than the corresponding fluorescence spectra. A large excited state dipole moment parallel to the smaller ground state dipole moment was calculated. The large dipole moment change with the strongly solvatofluorochromic behaviour, as the solvent polarity increases, demonstrates the formation of an intramolecular charge-transfer (ICT) excited state, which is confirmed by theoretical calculation using semiempirical PM3 method. Also, the effect of dye concentration on the electronic absorption spectra for the investigated dyes has been studied in ethanol. In addition, the acidochromic behaviour of these dyes has been studied using sulphuric acid at different H o values. A progressive red-shift in the absorption and emission spectra has been observed upon increasing the concentration of sulphuric acid with dramatic changes in colour. This suggests the design of potential optical sensors for probing acidity of the medium or water content in sulphuric acid. The calculated excited state protonation constants $\left( {\mbox{p}K_{\rm a}^\ast } \right)$ are lower than p $K_{\rm a\thinspace}$ values calculated for the ground state, indicating that the investigated ketocyanines become more basic in the first excited singlet state.

The inclusion behavior of an intramolecular charge transfer (ICT) fluorescent probe namely; 2-[3-(4-dimethylamino-phenyl)-allylidene]-tetralone (DMAPT) in organized assemblies of aqueous micellar, α- and β-cyclodextrins (CDs) and bovine serum albumin (BSA) pockets have been studied using steady-state absorption and fluorescence spectroscopy. The fluorescence characteristics (energy and intensity) of DMAPT are highly sensitive to the properties of the medium. The ICT maximum is strongly blue-shifted with a great enhancement of the fluorescence intensity upon addition of different surfactants, confirming the solubilization of DMAPT in the hydrophobic micellar assembly. In addition, the fluorescence of DMAPT is more sensitive to the nature and concentration of the added CDs. In α- or β-CD solutions, the fluorescence intensity increases strongly (by 6 and 23 orders of magnitude, respectively). Upon encapsulation in the CD cavity, the molecular flexibility decreases due to the geometrical restrictions of the CD nanocavity which decreases the non radiative transition via the free rotation around the single and/or double bonds of the butadiene bridge. This was supported by finding that the fluorescence quantum yield of DMAPT increases with increasing the viscosity of the medium. The binding constants of DMAPT with micelles, α- and β-CD solutions have been calculated and were found to be highly dependent on the nature of the used surfactants or CDs. The thermodynamic parameters have been also determined and the difference in magnitude between the formed α- and β-CD-DMAPT inclusion complexes is discussed on the basis of the cavity size. Finally, the binding constant of DMAPT with bovine serum albumin was calculated, indicating the relative stability of the DMAPT-BSA complex. The energy transfer distance between BSA as a donor and DMAPT as an acceptor was obtained following the fluorescence quenching of BSA by DMAPT, via resonance mechanism as a quencher.

Photophysical and intramolecular charge transfer characteristics of a new ketocyanine dye namely; 2-[3-(4-dimethylaminophenyl)-allylidene]-tetralone (DMAPT) have been studied in organic solvents having different polarities and hydrogen bond donating ability by using steady-state absorption and emission techniques. Spectral data show that increasing solvent polarity results in a significant solvatochromic shift in the absorption maxima and drastic red shifts in the fluorescence maxima, indicating an intramolecular charge transfer character (ICT) of the excited state, and that the solvent-induced dipole moment change is much greater in the excited state than in the ground state. Semiempirical calculations (PM3 and ZINDO/S) were employed to understand the geometric and electronic structure of DMAPT in both ground and excited state. It reveals twisted intramolecular charge transfer character of the excited state due to photoinduced electron transfer from the dimethyl amino group to the carbonyl oxygen. Also, in order to test the sensing properties and control the intramolecular charge transfer interaction of DMAPT, the complexation behavior of DMAPT in ground and excited states with Li + , Mg 2+ and Ca 2+ , has been studied in acetonitrile solutions. The results indicate ground state complex formation between metal ions and the dye. Values of the equilibrium constants for the interaction of metal ions with DMAPT in the S 1 state have also been estimated.

The host–guest complexation between a novel guest namely; 2-(4-pyridinylbenzothiazolyl) ethane, PBE and β-cyclodextrin was studied using steady-state absorption and emission techniques. The fluorescence maximum is strongly blue-shifted with a great enhancement in the fluorescence intensity upon addition of β-CD, confirming the formation of inclusion complexes. The solid inclusion complex between PBE and β-CD has been prepared, characterised using FT-IR, X-ray diffraction and scanning electron microscope techniques. PBE is encapsulated with β-CD nanocavity and 1:1 PBE–β-CD host–guest interaction is identified. This is confirmed using semi-empirical quantum chemical calculations. PBE guest entered into the less polar cavity through the benzothiazole moiety. The negative values of enthalpy and free energy changes suggest that the encapsulation process is thermodynamically favourable. Additionally, the fluorescence is more sensitive to the micellar medium, whether it was cationic, anionic or neutral as well as metal ions like, Li+, Cu2+ and Fe3+. Finally, the antimicrobial activities of PBE guest and its inclusion complex with β-CD host are studied.

A novel chalcone, namely 5-(4-(dimethylamino)phenyl)-1-(thiophen-2-yl)penta-2,4-dien-1-one, DMATP, and its complexes with nickel(II), vanadium(III), palladium(II) and platinum(II) metal ions were synthesized and characterized using a set of chemical and spectroscopic tools including elemental analysis, electrical conductance, magnetic susceptibility and spectral techniques. The interactions of the synthesized chalcone and its metal complexes with DNA were studied using steady-state absorption and emission techniques as well as viscosity and electrochemical measurements. The obtained results confirm DNA intercalation. Additionally, theoretical studies were performed for all the investigated compounds using DFT/B3LYP calculations. The optimized geometries are found to be in good agreement with the suggested experimental structures. The bond lengths, bond angles, chemical reactivity, energy components, binding energy and dipole moment were evaluated. Also, theoretical infrared intensities and thermodynamic parameters for all compounds were calculated. Molecular docking calculations show that the Ni(II) complex exhibits the highest DNA binding activity, which agrees well with the experimental results. Finally, the compounds were screened for antimicrobial activity using several microorganisms.