Behavior In Different Solvents Research Articles

Synthesis of Perylene Diimide Modified by POSS and its Assembly Behavior in Solution and SBS Matrix

In this work, Perylene diimide derivatives 1,7- POSS-PDI-C12 (PPC) were synthesized using 1,7-Br-PDI- C12, 18-crown-6 ether as phase transfer agent, K2CO3 as catalyst and THF as solvent in a reaction system. Subsequently, the POSS-SH group was successfully introduced into the perylene imide bay site in high yield. The chemical structure and molecular weight of the products were characterized by 1H-NMR, 13C-NMR, MALDI-TOF MS and FT-IR. The self-assembly behavior in different solvents was studied using the research solution self-assembly method. PPC remained in a single monomolecular state due to the bulky POSS group, which introduced large steric hindrance in the molecular packing, leading to the weakening of the π–π interactions. Then, the Composite thin films containing PPC in SBS was prepared. PPC do not exhibit significant force-chromic behavior owing to the dispersion of single- molecule states. This shows that in the construction of mechanochromic materials, chromophore molecules need to have a certain degree of aggregation in the matrix, but the aggregation degree should not be too high.

Rationally designed novel phenazine based chemosensor with real time Hg2+ sensing application

Phenazine derivatives have been explored in the selective detection of ions due to their binding ability with analytes. In this context, C-6 sulfenylated benzo[a]phenazine-5-ols (3a-d)have been synthesied and explored in sensing application. Initially, the molecules were designed by utilizing benzo[a]phenazin-5-ol as a core structure variably substituted with electronically diverse aryl thiols to investigate the substituent effect on their electrostatic properties. The ground state geometry of all the designed molecules was optimized with DFT using B3LYP/6-311G+(d,p) level of theory. Energy gap between FMOs was observed to be minimum and maximum for electron rich and deficient frameworks, respectively. The LUMO electron density in all the designed molecules except for compound bearing nitro group (3c) lies on the phenazine unit. This exceptional behavior enthusiased us to explore their photophysical properties. The compounds were synthesized and characterized using FT-IR, NMR and mass spectrometric techniques. In an attempt to examine their spectral behavior in different solvents, their absorption and emission spectra were recorded. The compounds exhibited absorptions maxima ranging between 475-514 nm, which shifted to longer wavelength while changing solvent polarity from CHCl3 to DMSO thus depicting positive solvatochromism. Similarly, the emission maxima was observed in a range of 570–685 nm with a maximum stokes shift of 6454 cm−1 for 3c. The compound 3c was further explored in the sensing application using DMSO:Water (60:40, v/v) mixture. A blue shift of 30 nm with nearly 7 fold increase in the emission intensity was observed upon addition of Hg2+ into 3c solution. Moreover, LOD of 21.9 nM and binding stoichiometry of 2:1 as determined by Benesi–Hildebrand and Job's plot establish the robust response of developed probe towards Hg2+ ion. The mechanism of complex formation was predicted by 1H NMR titration and DFT studies. Finally, the developed probe has been successfully utilized for sensing Hg2+ in real water samples.

The Effect of Branched Alkyl Chain Length on the Properties of Supramolecular Organogels from Mono-N-Alkylated Primary Oxalamides.

Mono-N-alkylated primary oxalamide derivatives with different sized branched alkyl tail-groups were excellent low molecular weight gelators for a variety of different organic solvents with different polarities and hydrogen-bonding abilities. Solvent-gelator interactions were analyzed using Hansen solubility parameters, while 1H NMR and FTIR spectroscopy were used to probe the driving forces for the supramolecular gelation. The molecular structures of the twin tail-groups did not significantly affect the supramolecular gelation behavior in different solvents. However, for select solvents, the molecular structures of the tail-groups did have a significant effect on gel properties such as the critical gelator concentration, thermal stability, gel stiffness, gel strength, network morphology, and molecular packing. Finally, metabolic activity studies showed that the primary alkyl oxalamide gelators had no effect on the metabolic activity of mouse immune cells, which suggests that the compounds are not cytotoxic and are suitable for use in biomedical applications.

From Unimolecular Template to Silver Nanocrystal Clusters: An Effective Strategy to Balance Antibacterial Activity and Cytotoxicity.

Silver nanomaterials have attracted a great deal of interest due to their broad-spectrum antimicrobial activity. However, it is still challenging to balance the high antibacterial efficiency with low damage to biological cells of silver nanostructures, especially when the diameter decreases to less than 10 nm. Here, we developed a new type of Ag nanohybrid material via a unimolecular micelle template method, which presents amazing antibacterial activities and almost noncytotoxicity. First, water-soluble multiarm star-shaped brushlike copolymer α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 was precisely synthesized and its micelle behavior in different solvents was revealed. Then, nanocrystal clusters assembled by Ag grains (Ag@Template NCs) were prepared through an in situ redox route using the unimolecular micelle of α-CD-g-[(PEO40-g-PAA50)-b-PEO5]18 as the soft template, AgNO3 as a precursor, and tetrabutylammonium borohydride (TBAB) as the reducing agent. The overall size of the achieved Ag@Template NCs is controlled by the template structure at around 40 nm (Dh in DMF), and the size of the Ag grain can be easily regulated from ∼1 to ∼5 nm by adjusting the feeding ratio of AgNO3/acrylic acid (AA) units in the template from 1:10 to 1:1. Benefitting from the structural design of the template, all Ag@Template NCs prepared here exhibit excellent dispersibility and chemical stability in different aqueous environments (neutral, pH = 5.5, and 0.9% NaCl physiological saline solution), which play a crucial role in the long-term storage and potential application in a complex physiological environment. The antibacterial and cytotoxicity tests indicate that Ag@Template NCs display much better performance than Ag nanoparticles (Ag NPs), which have a comparable overall size of ∼25 nm. The inhibitory capability of Ag@Template NCs to bacteria strongly depends on the grain size. Specifically, the Ag@Template-1 NC assembled by the smallest grains (1.6 ± 0.3 nm) presents the best antibacterial activity. For E. coli (-), the MIC value is as low as 5 μg/mL (0.36 μg/mL of Ag), while for S. aureus (+), the value is around 10 μg/mL (0.72 μg/mL of Ag). The survival rate of L02 cells and lactate dehydrogenase assay together illustrate the low cytotoxicity possessed by the prepared Ag@Template NCs. Therefore, the proposed Ag@Template NC structure successfully resolves the high reactivity, instability, and fast oxidation issues of the ultrasmall Ag nanoparticles, and integrates high antibacterial efficiency and nontoxicity to biological cells into one platform, which implies its broad potential application in biomedicine.

Katritzky salt fluorophores: Facile synthesis, bright solid-state emission, and mechanochromic luminescence

Katritzky Salts, readily synthesized from condensation between pyrylium salts and amines, were found to be bright solid-state fluorescent emitters. All these ionic fluorophores exhibited remarkable emission enhancement in the DMSO-H2O mixture with raising water fraction, which was identical to classical aggregation induced emission luminogens (AIEgens). After detailed investigation of their photoluminescence behavior in different solvents, the emission enhancement was attributed to polarity changes of solvent mixtures at low volume fraction of water, and aggregate formation at high volume fraction of water. Single crystal structures of TPP3 had directly indicated that the intermolecular π-π stacking interactions between fluorophores were severely suppressed as a result of their highly twisted structures, which had consequently contributed to the high emission quantum yield in the solid state. Furthermore, owing to intramolecular free rotations within these propeller-shaped ionic luminogens, obvious mechanochromic luminescence behavior was also observed with red-shifted emission after grinding and blue-shifted emission after solvent annealing.

Mechanism of an Elusive Solvent Effect in Organozinc Reagent Synthesis.

Solvent effects are often difficult to understand in cases where reaction intermediates, and thus their differential behavior in different solvents, are not directly observable by traditional ensemble analytical techniques. Herein, the sensitivity of single-particle fluorescence microscopy uniquely enables direct observation of organozinc intermediates and solvent effects on their build-up and persistence. When combined with NMR spectroscopy, these imaging data pinpoint the previously elusive mechanistic origin of solvent effects in the synthesis of widely used organozinc reagents. These findings characterize the acceleration of oxidative addition of the starting organoiodide to the surface of zinc metal in DMSO relative to THF, but once formed, surface intermediates display similar persistence in either solvent. The current studies are the first demonstration of a highly sensitive, single-particle fluorescence microscopy technique to pinpoint otherwise elusive solvent effects in synthetic chemistry.

Interplay of Spin Crossover and Coordination-Induced Spin State Switch for Iron Bis(pyrazolyl)methanes in Solution.

Bis(pyrazolyl)bipyridinylmethane iron(II) complexes show a versatile spin state switching behavior in different solvents. In the solid, the magnetic properties of the compounds have been characterized by X-ray diffraction, Mößbauer spectroscopy, and SQUID magnetometry and point toward a high spin state. For nitrilic solvents, the solvation of the complexes leads to a change of the coordination environment from {N5O} to {N6} and results in a temperature-dependent SCO behavior. Thermodynamic properties of this transformation are obtained via UV/vis spectroscopy, SQUID measurements, and the Evans NMR method. Moreover, a coordination-induced spin state switch (CISSS) to low spin is observed by using methanol as solvent, triggered through a rearrangement of the coordination sphere. The same behavior can be observed by changing the stoichiometry of the ligand-to-metal ratio in MeCN, where the process is reversible. This transformation is monitored via UV/vis spectroscopy, and the resulting new bis-meridional coordination motif, first described for bis(pyrazolyl)methanes, is characterized in the solid state via X-ray diffraction, Mößbauer spectroscopy, and SQUID measurements. The sophisticated correlation of these switchable properties in dependence on different types of solvents reveals that the influence of the solvent on the coordination environment and magnetic properties should not be underestimated. Furthermore, careful investigation is necessary to differentiate between a thermally-induced spin crossover and a coordination-induced spin state switch.

Detailed spectra, electronic properties, qualitative non-covalent interaction analysis, solvatochromism, docking and molecular dynamics simulations in different solvent atmosphere of cenobamate

Cenobamate, which is a voltage-gated sodium channel (VGSC) blocker, finds its full application in several anti-epileptic medications. This manuscript tries to look at the structure and other physicochemical properties of this compound with electronic structure methods and molecular mechanics tools. Density functional theory was used to optimise the ground-state geometry of the molecule using dispersion-corrected ω-B97XD functional using aug-cc-pVDZ basis sets, from which frontier molecular orbitals were studied. This study gave a myriad of information about the electronic properties and descriptors that are well enough to predict the bioactivity of the molecule. Electronic excitations between different energy levels, resulting from the interaction between the electrons and electromagnetic radiation, were analysed using time-dependent density functional theory with CAM-B3LYP functional. Numerous parameters like Fukui, ALIE and MESP provided an ample amount of information about the reactivity preferences of the molecule. Molecular docking studies predicted the biological activity of the molecule and its possible use as an anti-depressant. As it was found to show biological activity, its liquid-state behaviour in different solvents was mapped using molecular dynamics simulations.

Understanding solubility, spinnability and electrospinning behaviour of cellulose acetate using different solvent systems

The purpose of this study is to understand the solubility and spinnability of cellulose acetate (CA) and its electrospinning behaviour in different solvents. As the process of electrospinning and the corresponding fibre properties are primarily governed by the solvents used, a systematic study of the selection of solvent systems using the solubility parameters of Hildebrand and Hansen along with a Teas chart for a particular polymer is essential for the better optimization of the process. It appeared from the Teas chart that higher dispersion force \((f_{\mathrm{d}})\) and lower hydrogen bonding force \((f_{\mathrm{h}})\) are convenient for both the solubility and spinnability of CA in single solvent of acetone and binary solvent of 2:1 acetone/N,N-dimethylacetamide (DMAc). The viscosity of the solutions escalated with increasing concentration of CA due to polymer chain entanglement which in turn favoured fibre formation. Among the solvent systems used in this work, field emission scanning electron microscopy arrayed the electrospun CA fibres using pure acetone as a solvent produced both cylindrical- and ribbon-shaped fibres of a diameter of 1 \(\upmu \)m, whereas CA in 2:1 acetone/DMAc yielded smooth bead-free cylindrical fibres of diameter in the range of 250–350 nm and CA in 3:1 acetic acid/water formed fibres with beads. Rheological analysis showed that fibre formation improved with increasing viscosity of CA solution. Electrical conductivity measurement of the CA solutions depicted that with an increase in CA concentration, fibre diameters were increased, whereas the conductivity decreased. Also, attenuated total reflectance–Fourier transform infrared spectroscopy confirmed the major peaks of CA for all the electrospun samples.

A new macrocyclic ligand salt, 3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane dihydrobromide dehydrate [H 2 L B¢ ]Br 2 ·2H 2 O and some of its metal complexes – Synthesis, characterization and antimicrobial studies

Abstract The reaction of an isomeric ligand LB (a C-chiral isomer of 3,10-C-meso-Me8[14]ane) with dibromoxylene resulted in an unstable N-pendent ligand salt, [(H2LB¢-2H)(-CH2-C6H4-CH2-OH)2] Br2·CH3OH·H2O, which on recrystallization yielded a stable supramolecular ligand salt [H2LB¢]Br2·2H2O.The structure of the new ligand salt was confirmed by X-ray crystallography. The solid state structure of ligand shows that LB¢ is protonated at the N2 and N2A nitrogen atoms and the methyl groups of LB and LB¢ have the same axial and equatorial positions with slight changes in bond angles and bond lengths. The overall charge balance is provided by two bromide anions. In the solid state [H2LB¢]Br2·2H2O shows that the 3, 10 methyl groups are at axial positions and the 5,12 methyl groups at equatorial positions. LB¢ undergoes complexation with different metal salts to form the corresponding metal complexes [M(LB¢)Xm]Yn·xH2O, (M = Cu2+, Ni2+, Co3+, Zn2+, Cd2+ or Pd4+; X & Y = ClO4−, NO3−, Br−, Cl−, SCN−; m, n & x = 0, 1, 2). The metal complexes were characterized on the basis of elemental analyses; IR, UV–Vis and 1H NMR spectroscopy, magnetic and conductance data. These complexes showed different electrolytic behavior in different solvents. The antibacterial and antifungal activities of the ligand LB¢ and its complexes toward different phytopathogenic bacteria were investigated.

Synthesis of organic-inorganic hybrid compounds and their self-assembled behavior in different solvents

Self-assembly behavior of polyoxometalates (POMs) is influenced by the functional group linked with polyoxometalates structure. We modified the POMs with organic molecule terpyridine to endow POMs the ability to assemble into nanostructure and control the properties of POMs. An amphiphilic organic-inorganic hybrid compound was prepared through combining the 4′-para-phenylcarboxyl-2,2′:6′,2′′-terpyridine (PPCT) with POM to form the (TBA)3POM-PPCT. After cationic exchange, tetrabutylammonium cation (TBA+) can be turned into H+ to produce H3POM-PPCT. H3POM-PPCT showed excellent self-assembly behavior in different solvents. By adjusting the proportion of solvents, different fibers and leaf-like aggregates were obtained, which were determined by SEM and TEM observations. According to the experimental observations, mechanism of the formation of nanostructures was established. The redox properties of POMs can be maintained after the modification with PPCT, which were demonstrated by cyclic voltammetry (CV) measurements. The successful synthesis of these POMs may provide us an opportunity to find more functionalized ramifications of POMs, with self-assembled structures controlled in different solvent, but the interesting properties of these novel POMs can also provide motivation and guidance for the further development of novel functionalized POMs.

Solvent Dependent Luminescence Sensing of Nitro‐Explosives by a Terbium‐Based Metal‐Organic Complex

AbstractPowder sample of a terbium based metal‐organic complex (MOC) [Tb2(pydcH)6]⋅3H2O {H2pydc= 2,6‐Pyridinedicarboxylic acid}, 1, were synthesized by simple solvent evaporation method in water medium. Powder X‐ray diffraction data of complex 1 confirmed a molecular complex of tricapped trigonal prismatic Tb3+ ion with a free carboxylic acid site of each H2pydc ligands by comparing with the single crystal X‐ray diffraction data of isomorphous europium based compound, [Eu2(pydcH)6]⋅3H2O. Compound 1 showed very strong visible green luminescence which was sensitive towards nitro explosives; and interestingly, the sensitivity was dependent on the solvent used. The luminescence was emitted by ligand sensitized Tb metal centre of compound 1 and was quenched so quickly and efficiently that an instant colour change from visible green to colourless was observed by naked eye. The experiments were done for the detection of nitro‐explosive materials such as 2,4,6‐trinitrophenol (TNP), 2,4‐dinitrophenol (2,4‐DNP), 2,4‐dinitro toluene (DNT), 1,3‐dinitro benzene (DNB), 4‐nitrotoluene (NT) and nitro benzene (NB) in water (H2O), methanol (MeOH), acetonitrile (CH3CN), and tetrahydrofuran (THF) solvents. Mechanism of the luminescence quenching behaviour in different solvents was successfully explained by combined effect of resonance energy transfer, absorption of excitation light and the possibility of electron transfer. Experimental results were also supported by DFT calculations.

Insights on the solvatochromic effects in N-doped yellow-orange emissive carbon dots

We have demonstrated a rapid and facile synthetic method to prepare N-doped Cdots that has excitation independent-emission in yellow-orange region. The Cdots showed solvatochromic behavior in different solvents due to change in solvent polarity illustrating n → π* transition (edge band).

Solvent and substituent effect on the photophysical properties of pyrazoline derivatives: A spectroscopic study

Abstract Pyrazoline derivatives are among solvatochromic dyes and they are the most widely used in many fields such as sensors, labeling agent and optoelectronic devices. Therefore, synthesis of new pyrazoline derivatives and determination of their optical behavior in different solvents are a very important research area. In this study, the solvatochromic behaviors of seven new synthetic pyrazoline derivatives, (4-[3-(4-Hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamides, compound 1-7), were determined in different solvents. As a result of the measurements, a large red shifts in the fluorescence spectra of the compounds studied were observed for each compound, when the polarity of the solvent increased. Kamlet-Taft and Catalan parameters were used to describe the solvent-soluble interactions. The obtained results showed that the solvatochromic behavior of the compounds is dependent on their solvent polarity as well as the effect of the hydrogen-bonding properties of the solvents. It was also found that the increases in the polarity of the solvent was facilitated the non-radiative transition. Furthermore, the changes in the dipole moments of compounds 1-7 in different solvents at room temperature were calculated by using the Lippert–Mataga equation. It was very impressive that calculated fluorescence quantum yield values of the compounds studied here by using different solvents were remarkably high than the ones reported in the literatures for pyrazolines. In addition, the effect of substituent on the photo-physical properties of the compounds was also investigated. It was observed that the fluorescence intensity of the substituted compounds 2-6 increased comparing to the compound 1, which is a non-substituted derivative. These changes were not dependent on electronic nature of the substituent on phenyl ring (i.e. electron donating and electron withdrawing substituent). According to data obtained it can be stated that these novel solvatochromic dyes studied here can be find application in pharmaceutical industry, as labeling agent, sensor applications as biosensors or analytical sensors and/or optoelectronic devices.

Synthesis and Photophysical and Anion‐Sensing Properties of Triarylborane‐Substituted Cross‐Conjugated and Conjugated Thienothiophenes

Two novel organoboron compounds BBTT1 and BBTT2 possessing conjugated thieno[3,2‐b]thiophene and cross‐conjugated thieno[2,3‐b]thiophene, respectively, as electron donors (D) and bis‐triarylboron units as electron acceptors (A) linked through thiophene π spacers have been synthesized and structurally characterized by various spectroscopic methods. The donor capabilities of the thienothiophenes were examined in view of their electrochemical and photophysical properties. Also, their solvatochromic behaviour in different solvents as well as their anion‐recognition ability have been thoroughly investigated. Compounds BBTT1 and BBTT2 act as colorimetric and fluorescent chemosensors with high sensitivity and selectivity towards F–. Furthermore, BBTT1 displays a peculiar redshift in fluorescent titration experiments upon the binding of F– to the borane moiety, and “turned‐on” chemosensor character for the detection of fluoride, as illustrated by the accompanying change in emission colour. On the other hand, the binding of F– to BBTT2 reveals a “turned‐off” sensor property. The electronic and structural characteristics of the two compounds and their fluoride‐sensing properties were assessed by means of DFT computations.

Synthesis, characterization and antibacterial studies of zinc(II) complexes with hexamethyl-tetraazacyclotetradecadiene Me6[14]diene and C-chiral isomers of its reduced analogue

The ligand salt, Me6[14]diene·2HClO4 (L·2HClO4) was prepared by condensation of acetone and ethylene diamine in the presence of perchloric acid. On reduction of this diene ligand salt, L·2HClO4 with sodium borohydride, the two isomeric ligands, ‘tet-a’ and ‘tet-b’ were produced. The ligands, on reaction with ZnX2 (X=Cl, ClO4, NO3 or CH3COO) and ZnSO4 produced the corresponding complexes. These complexes have been characterized on the basis of elemental analyses; IR, UV–Vis and 1H-NMR spectroscopies; magnetic and conductance data. Based on these data, all of the complexes of the diene ligand L, as well as the perchlorate complexes of all of the ligands attained a square-pyramidal arrangement, whereas the complexes of ‘tet-a’ and ‘tet-b’, with X=NO3, Cl or CH3COO and with ZnSO4 salt, were octahedral. Moreover, all complexes were monometallic except the nitrato complex, [(ZnL)2(µ-NO3)](ClO4)3 which is bimetallic. The structure of [(ZnL)2(µ-NO3)](ClO4)3 has been confirmed by X-ray crystallography. In this complex the zinc centres lie within a N4O donor set, with the four nitrogen donors from L and one of the oxygen atom stemming from the bridging NO3. The complexes show different electrolytic behavior in different solvents. The antibacterial activities of the ligands and complexes towards different phytopathogenic bacteria have been investigated.

Synthesis, structure, spectral properties and DFT quantum chemical calculations of 4-aminoazobenzene dyes. Effect of intramolecular hydrogen bonding on photoisomerization

In this paper three different “push-pull” 4-aminoazobenzene dyes have been synthesized in order to characterize their photochromic behavior in different solvents. The molecular geometry was optimized by DFT/B3LYP functional combined with the standard 6–31+G(d,p) basis set for trans (E) and cis (Z) isomers and the energy levels of HOMO and LUMO frontier orbitals were computed using IEFPCM solvation in CHCl3 and DMF. The calculated results were compared to the experimental optical band gap and HOMO values of cyclic voltammetry. The intramolecular six-membered hydrogen bond was formed in both isomers of the synthesized dyes. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H298 (sum of electronic and thermal enthalpies), free Gibbs energy G298 (sum of electronic and thermal free Gibbs energies) and dipole moment μ were computed for trans (E) and cis (Z) isomers in order to estimate the ΔEtrans→cis, Δμtrans→cis, ΔHtrans→cis, ΔGtrans→cis and ΔStrans→cis values. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. The solvatochromic shift was evaluated by UV-VIS spectroscopy in CHCl3 (nonpolar), EtOH (polar protic) and DMF (polar aprotic) solvents to determine the electron withdrawing and donating properties of the substituents on electron transitions energy. Through the increasing solvent polarity a strong bathochromic shift is observed. The photoisomerization experiments have been performed in two solvents CHCl3 (nonpolar) and DMF (polar aprotic) by UV light irradiation with λ=365nm at equal concentrations and time of illuminations. The electronic spectra were computed by TD-DFT after geometry optimization using IEFPCM solvation in CHCl3 and DMF. The degree of photoisomerization was calculated for the three azo chromophores in both solvents. By using first derivative of the UV-VIS spectra it was possible to resolve the overlapped electron transitions absorption bands. The existing intramolecular hydrogen bond in the azo chromophores was discussed in relation to the isomerization mechanisms and relative stability of the cis (Z) isomers.

Molecular dynamics simulations and 2D-NOESY spectroscopy studied on conformational features of ACE-inhibitory tripeptide Gly-Glu-Phe in aqueous and DMSO solutions

Molecular dynamics simulations and 2D-NOESY spectroscopy were applied to study the conformations and hydrogen-bonding interactions of ACE-inhibitory tripeptide Gly-Glu-Phe (GEF) in aqueous and DMSO solutions. The properties of GEF in simulations were characterized by intramolecular distance, root-mean-square deviation, solvent-accessible surface, and radius of gyration. Interestingly, the GEF molecule showed different behavior in different solvents. In aqueous solution, the GEF was highly flexible, and it could quickly convert from extended state to folded state. However, in DMSO solution, the extended conformations were hardly observed. The GEF molecule preferred extended state in aqueous compared to DMSO solution, which was confirmed by 2D-NOESY.

Synthesis, Characterization And Electrolytic Behavior Of Cadmium(II) Complexes Of 5,7,7,12,14,14- Hexamethyl-1,4,8,11-Tetraazacyclotetradeca-4,11- Diene And Isomers Of Its Saturated Analogue

Condensation of ethylendiamine with acetone in the presence of quantitative amount of perchloric acid, yielded the ligand 5,7,7,12,14,14- hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene dihydroperchlorate (denoted by L.2HClO4). The ligand L.2HClO4 on reduction with NaBH4, yielded an isomeric mixture of saturated macrocycles, the Me6[14]anes, which were resolved into two distinct C-chiral isomers (denoted by ‘tet-a’ and ‘tet-b’). Interaction of ligands L.2HClO4, ‘tet-a’ and ‘tet-b’ with salts CdI2, Cd(NO3)2.4H2O, CdCl2.2H2O and Cd(ClO4)2.6H2O produced different five coordinated square pyramidal and six coordinated octahedral cdmium(II) complexes. Among them the complexes, cis-[Cd(teta)( NO3)](NO3) and cis-[Cd(tet-b)(NO3)](NO3) underwent axial ligand substitution reaction with KCNS; whereas complex [Cd(tet-a)I2] underwent axial ligand substitution reaction and complex [CdLI](ClO4) underwent simultaneous ligand substitution and addition reaction with NaNO2. Characterization of all the complexes were carried out on the basis of elemental analysis; FT-IR, UV-Vis. and 1H-NMR spectroscopy; melting point determination as well as by magnetic moment and conductivity measurements. Molar conductivity measurment of the complexes reavealed that they show different electrolytic behavior in different solvents.

Dispersion behavior and the influences of ball milling technique on functionalization of detonated nano-diamonds

Possessing unique characteristics such as super hardness, excellent chemical stability, thermal conductivity and biocompatibility, nanodiamonds are promising materials. High surface energy and the presence of impurities on the surface of detonated nano-diamonds (DNDs) cause agglomeration and poor dispersion in different solvents preventing its commercial exploitation. Functionalization of DNDs is an important technique for making DNDs suitable for commercial applications. Normally, the functionalization of DNDs with triethylene-tetra-amine (TETA) and acids is time consuming. In this work, ball milling has been performed with different milling media (NH4HCO3, NaCl and sucrose) and investigate the effect of different milling media on DNDs de-aggregation followed by its dispersion behavior in different solvents (ethanol, water and dimethyl sulphoxide (DMSO)). Furthermore, aminated DNDs (A-DNDs)/epoxy composites have been fabricated which perform outstandingly in mechanical behavior owing to the better dispersion of milling media assisted A-DNDs in epoxy. Our results indicate that NaCl grains as milling media is better than sucrose, which results in an improved mechanical response of resultant composites on account of its better dispersion and de-aggregation of A-DNDs in epoxy. Therefore, ball milling being fast and controllable technique assists in de-aggregation of A-DNDs in the presence of milling media.