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Heavy metals are particularly damaging contaminants in the environment, and even trace concentrations represent a risk to human health due to their toxicity. To detect the heavy metals of Mn2+ and Co2+ ions, a novel selective reusable paper-based Fluorescence naked-eye sensor based on naphthalene cationic Schiff base (NCSB) was synthesized and confirmed using FT-IR, 1 H-NMR, and MS tools. Based on a blue to colorless color change in the aqueous solution, the NCSB sensor is utilized to Mn2+ and Co2+ cations selectively among other metal ions (Fe2+, Cu2+, Mg2+, Ni2+, Zn2+, Cd2+, Hg2+, Pb2+, Sn2+ and Cr3+). In the aqueous medium, the NCSB sensor displayed high sensitivity, with limits of detection (LOD) values of 0.014 µM (14.08 nM) and 0.041 µM (41.47 nM) for Mn2+ and Co2+ cations, respectively. The paper-based sensor naked-eye detected Mn2+ and Co2+ cations in water at concentrations as low as 0.65 µM (65 nM) and 0.086 µM (86 nM), respectively. It was discovered that 5 min of incubation time and a pH range of 7 to 11 were optimal for the complexation reaction between the Mn2+ and Co2+ ions and the NCSB sensor. Through a static quenching process, the interaction of the different metal ions with the Schiff base group in the NCSB molecule results in the development of a ground-state non-fluorescent complex. NCSB sensor was also successfully applied in analysis of Mn2+ and Co2+ in environmental water with good recoveries of 94.8–105.9%. The theoretical calculations based on density functional theory (DFT) studies are in support of experimental interpretations. The links between the input factors and the anticipated response were evaluated using the quadratic model of the response surface methodology (RSM) modeling. [ABSTRACT FROM AUTHOR]

Siderophores are promising ligands for application in novel recycling and bioremediation technologies, as they can selectively complex a variety of metals. However, with over 250 known siderophores, the selection of suiting complexants in the wet lab is impractical. Thus, this study established a density functional theory (DFT) based approach to efficiently identify siderophores with increased selectivity towards target metals on the example of germanium and indium. Considering 239 structures, chemically similar siderophores were clustered, and their complexation reactions modeled utilizing DFT. The calculations revealed siderophores with, compared to the reference siderophore desferrioxamine B (DFOB), up to 128 % or 48 % higher selectivity for indium or germanium, respectively. Experimental validation of the method was conducted with fimsbactin A and agrobactin, demonstrating up to 40 % more selective indium binding and at least sevenfold better germanium binding than DFOB, respectively. The results generated in this study open the door for the utilization of siderophores in eco-friendly technologies for the recovery of many different critical metals from various industry waters and leachates or bioremediation approaches. This endeavor is greatly facilitated by applying the herein-created database of geometry-optimized siderophore structures as de novo modeling of the molecules can be omitted. [Display omitted] • DFT successfully predicts siderophore selectivity for critical metals (In and Ge). • Agrobactin and fimsbactin A were identified as promising siderophores for metal recovery. • Experimental validation confirms computational predictions of siderophore binding properties. • A siderophore-based approach offers potential for sustainable metal recovery and bioremediation. • The established methodology can be applied to identify siderophores for other metals [ABSTRACT FROM AUTHOR]

The solution state of a new antituberculosis drug 1,6-bis(hydrazidomethylsulflnyl)hexane (L) and its complexation with copper(II) were investigated by spectrophotometry, pH-potentiometry (T = 25 °C; at variable ionic strength), and mathematical modeling. The dissociation constants of the protonated and imidol forms of compound L were determined. Complexation reactions in the Cu2+—L system result in mononuclear complexes [CuL]2+ and [CuL2]2+ with the amide form of the ligand provided that the redox reactions are excluded. The most probable (optimized) structures of 1,6-bis(hydrazidomethylsulfinyl)hexane and its complexes were obtained from quantum chemical calculations within the framework of the density functional theory (PBE/6-311G (d) method). Compound L adopts a folded conformation. The coordination site of the 1:1 complex includes six oxygen atoms from two carbonyl groups, two sulfoxide groups, and two water molecules. In the 1:2 complex, each ligand molecule is coordinated in bidentate mode through the carbonyl oxygen atom and the primary amino nitrogen of a hydrazide fragment. [ABSTRACT FROM AUTHOR]

Separation of adjacent actinides (An) americium and curium is a critical and challenging step in advanced nuclear fuel cycles. Herein, we performed a quantum chemical calculation to explore the separation behavior of Am(III) from Cm(III) by two representative amide-type ligands, N,N′-dimethyl-N,N′-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) and N,N,N′,N′,N″,N″-hexaalkyl-nitrilotriacetamide (NTAamide). It was found that the better energy match of Am 5f orbitals and O, N 2p orbitals of the amide-type ligands resulted in the selective ability of these ligands to Am3+ over Cm3+. Complexation reaction analysis predicted that An(DMDOHEMA)2(NO3)3 and [An(NTAamide)2]3+ were the most probable species in the separation processes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Binding of group IA/IIA cations to N -phenylaza-15-crown-5 substituted Schiff bases. • Spontaneous complexation process in the gas phase for all metal cations. • Spontaneous complexation process for the smaller cations in acetonitrile. • More negative ΔG values for the complex formation with group IIA metal cations. Abstract N -Phenylaza-15-crown-5 containing Schiff bases act as excellent ligands for alkali and alkaline-earth metal ions. The complex formation ability of two differently N -phenylaza-15-crown-5 substituted Schiff bases has been investigated using density functional theory methods. The structures of the ligands and of the respective complexes with alkali and alkaline earth metal ions have been optimized and the thermodynamic parameters of the complex formation reactions have been determined. According to the obtained results there is a rough correlation between the metal cation radius and ΔG values in the gas phase and in acetonitrile solution: the smaller the cationic radius is, the more thermodynamically favorable is the complex formation. The results for the Gibbs free energy of the complex formation reaction of these ligands with seemingly ordinary structure with IA and IIA group metal ions indicate a spontaneous and energy-favorable process in the gas phase (for all metal cations) and in the acetonitrile environment (for the smaller ones). [ABSTRACT FROM AUTHOR]

Abstract A thymine moiety as ion binding accepter was introduced into asymmetric squaraine fluorophore by amide coupling reaction to develop a new thymine-squaraine based fluorescent chemosensor (SQ). Its detection ability towards heavy metal ions was investigated by UV–vis and fluorescent spectrometry. The results showed that the sensor had high selectivity towards Cd2+ over the other metal ions in aqueous media. Moreover, it was shown that the turn on fluorescence signal occurred in the present of high concentration of cationic surfactant hexadecyl trimethyl ammonium bromide (CTAB) solution which resulting in deaggregations of SQ. The stoichiometric ratio was determined by Job's plot analysis as 1:1 and the binding constant as 2.03 × 103 M−1 for the complex between Cd2+ and SQ was further calculated by the Benesi-Hilderbrand plot. The complexation mechanism was proposed according to ESI-MS and NMR results. The following DFT calculation fully supported that the detailed coordination mode of Cd2+ and SQ went through six-membered carbonyl oxygen and the C O group in the amide chain. Finally, the SQ sensor was successfully applied in waste water sample analysis. Graphical Abstract A new thymine-squaraine based turn on fluorescent probe has been developed for detecting Cd2+ ions on CTAB controlled squaraine aggregation. Unlabelled Image Highlights • A new near infrared thymine-squaraine based chemosensor SQ has been synthesized for Cd2+ detection. • 5-fold enhancements of turn on fluorescent signal for exclusive detection of Cd2+ can be observed. • The LOD was determined as 104 nM by tuning the surfactant controlled squaraine aggregation. • The chemosensor has proven to be applied in the industrial waste water analysis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Complexation of N -Benzoyl-ß-phenylisoserine (LC) with the excess cells Ca2+ ion is investigate at DFT and DFTD theories. • Nine stable of Ca2+ with LC complexes Interaction and complexation energies are presented. • NBO analysis has been done to explain the nature of metal-ligand co-ordination. • Complexation between LC and Ca2+ is mainly stabilized by electrostatic as well as orbital interactions. Abstract Taxol (Paclitaxel) has been shown experimentally to counteract the depolymerization of microtubuline induced by calcium ions (Shigemori and Kobayashi, 2004) and hence to reduce the proliferation of cancer cells. In this work, we study at the molecular level by means of theoretical tools the interaction of Ca2+ with the lateral chain of Taxol. Geometrical structure, interaction energy and wave function analysis are performed for all possible complexes. Our results show that two Taxol molecules can interact with a single calcium ion. This study is devoted to give new insights to rationally design new synthetic drugs. [ABSTRACT FROM AUTHOR]

The problem of legacy alkaline high-level waste (HLW) both in the US and Russia, as a result of weapons production, has prompted studies of ligands for extraction of actinides, that could be possibly used in the future together with Cs extractants for combined HLW extraction processes. The tripodal trisulphonamide ligand 1,3,5-tris-(4-(iso-propyl)-phenylsulfamoylmethyl)benzene (4-iPr-tsa), which has pre-organised functional groups for An(III) binding was synthesised and studied for potential Sm(III) and Am(III) binding and extraction by theoretical (DFT) and experimental (extraction) methods (for Sm(III) only). Both theory and experiments suggest that even though this family of ligands shows promise for Ln(III) and An(III) binding with minima for complex formation, complexation is competing with hydrolysis, and extraction is only feasible in alkaline solutions, in the presence of high concentrations of nitrate ions. Nevertheless, up to 51.8% of Sm(III) was removed under optimal conditions (NaOH = 2 × 10−4 M, NaNO3 = 0.1 M, [Sm]init = 5 × 10−5 M). Quantum chemical calculations demonstrate that the extraction of Sm(III) and Am(III) from the aqueous phase in the form of [M·(H2O)4·(OH)2·(NO3)] to the organic phase in the form of [M·4-iPr-tsa·(H2O)3] is thermodynamically favourable. Theory also shows that Sm(III) is a reasonably good surrogate for Am(III), as the optimised structures of the Sm and Am complexes show remarkable similarities. Even though the ligand was designed with the goal of introducing favourable cation-arene interactions, along with the expected N-binding mode of the ligand in its deprotonated form, it was found that these cation-arene interactions are rather weak in this case, and coordination with O atoms of the sulphonamide, and external water molecules, is favoured instead. [ABSTRACT FROM AUTHOR]

We applied density functional theory calculations to Am(III) and Eu(III) complexes with chalcogen-donor ligands of the formula N(EPMe2)2− (E = O, S, Se, Te). We calculated the equilibrium structures and relative stabilities of the complexes in the complexation reaction. The results indicated that the tendency of the relative stability is O ≪ S ~ Se ~ Te, which is consistent with the trend of soft acid classification. Molecular orbital overlap population analysis suggested that this tendency can be correlated with the bonding type in the covalent interaction between the f-orbitals of the metal atom and the chalcogen-donor atoms. [ABSTRACT FROM AUTHOR]

1,10-N, N ′-bis-(β- d -ureidoglucopyranosyl)-4,7,13-trioxa-1,10-diazacyclopentadecane is a new, recently synthesized compound, which exhibits complexation ability towards drugs. In the present study various theoretical methods, including molecular mechanics, computer simulations, semiempirical and DFT calculations, are applied to find the lowest energy conformers of this molecule in vacuo and in aqueous solution. For the most stable structures the vibrational frequencies as well as the C and H chemical shifts were computed. Along with the theoretical investigation the IR in the KBr discs and the NMR spectra in water and in pyridine were experimentally recorded. It is shown that in the lowest energy structures the two glucosyl units are placed on the same side of the diazacrown ring with their mutual orientations favoring formation of hydrogen bonds. The “open” structure, in which no such hydrogen bonds can be formed, is found to have much higher energy. The computed and measured IR spectra and NMR chemical shifts are compared and discussed in detail. The most stable structures are analyzed with respect to the possible mechanism of complexation of drugs. [ABSTRACT FROM AUTHOR]

Chromium bisanthracene‐η6 complexes are considered within the framework of density functional theory using LANL2DZ and 6‐31+G(d) basis sets and B3LYP functional. The complexation with both the same types of rings of anthracene decks (AA‐ and BB‐type complexes) and with different rings (AB‐type complex) are considered. The optimized geometries and the associated quantum chemical properties are comparatively discussed for the both types of basis sets used. LANL2DZ basis set yielded some unreasonable results. B3LYP/6‐31+G(d) level of calculations yielded the stability order as AA > BB > AB. IR spectra of AA and BB‐type complexes resemble each other. The C–H frequencies are almost the same for both of the anthracene decks, whereas they differ in the case of AB‐type complex. UV/Vis spectra of the complexes all absorb above 500 nm. AA and AB‐type complexes in contrast to BB‐type display rather complex pattern. The NICS(0) values of various rings in the complexes considered are obtained and discussed. [ABSTRACT FROM AUTHOR]

Complexation of a new macrocyclic compound, 2,6-dimethylformamide-calix[4]pyridine (L1), with Eu(III) was studied by spectrophotometry. Stability constants of the Eu(III)/L1 complex in different solvents were determined. The results reveal that L1 forms moderately strong complexes with Eu(III) and other lanthanides in aprotic solvents and shows little binding ability with transition metals. Moreover, the binding strength of L1 weakens significantly in protic solvents. Using 2-bromodecanoic acid as the synergistic reagent, L1 extracts Am(III) and Eu(III) successfully with a separation factor of SFAm/Eu=1.3, and the distribution ratios of Am(III) and Eu(III) increases as the aqueous acidity is decreased. DFT computational studies were conducted to corroborate the solvent extraction data, and compare the coordination properties of Am(III)/Eu(III) complexes with L1 and a related, 2,6-diformamide-calix[4]pyridine (L2). The computational results suggest that L2 could form stable complexes [ML]3+ and ML(NO3)3 [where M represent Am(III) or Eu(III)] in aqueous phase, in sharp contrast to the case of L1 where such complexes in aqueous phase are not stable. [ABSTRACT FROM AUTHOR]

The chelating agents for Al 3+ and Fe 3+ metal cations with therapeutic applications have been considered in the recent years. In designing of the hydroxypyridinones (HPOs) as the therapeutic chelating agents for iron and aluminium overload pathologies, quantum mechanical (QM) calculations are necessary for predicting the binding energies and thermodynamic parameters of the metal−HPO complexes. Three derivatives of the HPOs called 3-hydroxy-1,2-dimethylpyridin-4(1H)-one (DFP), 3-hydroxy-4(1H)-pyridinone (HOPO) and 5-hydroxy-2-(hydroxymethyl)pyridin-4(1H)-one (P1) were investigated for complexation with Fe 3+ and Al 3+ metal ions. Because of the maximum interaction between Fe 3+ and HPOs, all HPOs form stable complexes with Fe 3+ metal ion. Moreover, it was found that [Fe−P1] 2+ is a more stable complex than [Fe−DFP] 2+ and [Fe−3,4-HOPO] 2+ in the gas phase and water, confirming that P1 is the strongest selective iron chelator. The more stability of [Fe−P1] 2+ was attributed to an intramolecular hydrogen bond formation between the hydrogen atom of NH group and the oxygen atom of CH 2 OH chain. All complexes of the HPOs with Fe 3+ and Al 3+ were formed through the oxygen atoms of the C O and O H groups of the HPO. Natural bond orbital analysis showed that the interaction of the lone pair electrons of the oxygen atom of the chelator and antibonding orbitals of the Al 3+ and Fe 3+ are important in the complex formation. Topological parameters at the bond critical points confirmed the effective interaction between the Al 3+ and Fe 3+ metal ions and HPO as well as the nature of the metal−oxygen bonds. [ABSTRACT FROM AUTHOR]

Quantum chemistry calculations indicate that BN nanocage is a good candidate for selective complex formation with Li+in the presence of different alkali metal ions. Density functional theory (DFT) calculations were applied at the M05-2X/6-311++G(d,p) level of the theory to investigate the interaction of the B12N12nanocage (BN) and alkali metal ions (Li+, Na+, K+, Rb+and Cs+) in the gas phase and in water. On the basis of the results, BN nanocage is able to form a selective complex with Li+. Water, as a solvent, reduces the stability of the metal ion-BN complexes in comparison with the gas phase. Natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) analyses, reveal that the electrostatic interaction between the BN and metal ions can be considered as the driving force for complex formation in which the role of water is of significance. Density of states (DOSs) analysis of the BN nanocage structure in the presence of different metal ions showed a noticeable change in the frontier orbitals, especially in the gas phase, and Fermi level shifting toward the lower values. [ABSTRACT FROM AUTHOR]

[Display omitted] • Complexation rather than oxidation by ferrate and hydroxyl radicals dominated the removals. • Tetracyclines-Fe complexes contributed to 79% removal of four tetracyclines. • Experimental and theoretical studies confirmed the formation of tetracyclines-Fe complexes. • Thermodynamic and kinetic calculations showed the leading role of complexation. • Order of complexation rates distinguished the removal ratios of four tetracyclines. Complexation of tetracyclines with Fe species can be expected during oxidation by ferrate and be part of the complicated reactions that lead to the transformation of tetracyclines. Herein, we focused on the role of complexation in four tetracyclines removals by ferrate. The quenching experiment, desorption experiment, total organic carbon detection, and UV absorbance characterization demonstrated that, for the removal of tetracyclines, the complexation of tetracyclines with Fe3+ (derived from the reduction and decomposition of ferrate) contributed ∼79 %, followed by ∼11 % oxidation and ∼10 % adsorption/flocculation. Density functional theory calculations rationalized the formation of Fe-tetracyclines complexes and reactions of ferrate and hydroxyl radicals with each tetracycline. Thermodynamic and kinetic calculations indicated that complexation reactions between Fe3+ and tetracyclines were more likely to occur than oxidation reactions between ferrate and hydroxyl radicals. The complexation rate was highest for tetracycline and lowest for chlortetracycline, and the order of complexation rates was consistent with the experimental removal ratios of four tetracyclines. Complexation rates of tetracyclines with Fe3+ determine the removal of multiple tetracyclines by ferrate rather than oxidation rates. Insights based on forming Fe-tetracyclines complexes differed from the reported oxidation mechanisms, and complexation cannot be negligible in removing pollutants due to the potential secondary release. [ABSTRACT FROM AUTHOR]

Due to complexity arising from the presence of various rare tautomers and multiple protonation sites, little is known of the proton-bound heterodimers of guanine (G) and cytosine (C) that may exist in the gas phase. We extensively explored structures and energies of the heterodimers by density functional theory using the B3LYP functional, wherein rare tautomers of G and C that were predicted to be energetically accessible were considered in possible heterodimer structures. This extensive search found more than 90 stable structures for the proton-bound heterodimers, where various types of base-pairings were observed. For the six lowest energy structures that lie within 3 kcal/mol in energy from the most stable structure, ionic hydrogen bonding was found to be involved in base-pairing. The non-covalent complexation energies of the heterodimers were found to be quite strong at 40-50 kcal/mol. Some pairs of the heterodimers were connected by simple proton transfer in the ionic hydrogen bond as well. In addition, a Hoogsteen base pair was predicted to be the most stable conformer in the gas phase with a more than 90% population. Solvent field effects also suggested that the Hoogsteen base pair is one of the most stable conformers in an aqueous environment. Thus, we suggest that the Hoogsteen base pair is the most predominant form of the proton-bound heterodimers of G and C that may exist in the gas phase. [ABSTRACT FROM AUTHOR]

A water-soluble ferric (Fe 3+ ) ion sensor probe has been synthesized using one-pot multicomponent Hantzsch synthesis, followed by Cu (I) catalyzed “Click reaction”. The synthesized probe C1 shows selective binding towards Fe 3+ ion through a turn-off fluorescence response among various metal ions tested in aqueous medium. C1 shows an average fluorescence lifetime of 4.9 × 10 −10 s, and its selectivity towards Fe 3+ ion has also been studied by Stern-Volmer plot, detection limit and binding studies. The probe C1 forms a 1:1 complex with Fe 3+ ion with an association constant of (K a = 2.50 × 10 3 M −1 ), as evident from the Benesi-Hildebrand plot. Density Functional Theory (DFT) studies of the probe reveal a square pyramidal geometry. Both Fe 2+ and Fe 3+ bind strongly to the probe, but the complexation energy with Fe 3+ is almost double that with Fe 2+ , validating the experimental results. The probe C1 has also been tested for its application in biological systems and the results of an anti-proliferation assay of the fluorescent probe C1 in the absence and presence of FeCl 3 on various cell lines normal (L929) and cancerous (MCF-7, MDA-MB 231, A549 and HepG2) shows that the probe C1 would be non-cytotoxic, both in the absence and presence of Fe 3+ ions in the cells. [ABSTRACT FROM AUTHOR]

Noncovalent interactions of free-base phthalocyanine (HPc) with closed-cap armchair (5,5) and zigzag (10,0) single-walled carbon nanotubes (ANT and ZNT, respectively), as well as, for comparison, with C and C( I ) fullerenes, whose hemispheres were used to close the ends of nanotube models, were studied theoretically by using one pure dispersion-corrected GGA functional (PBE with a long-range dispersion correction by Grimme, or PBE+D) and two hybrid meta exchange-correlation functionals (M05-2X and M06-2X). Strong complexation was observed in all four systems studied. The general trend found is that the interaction strength increases with the size (number of C atoms) of carbon nanocluster, that is, in the order of ZNT > ANT > C > C. Depending on the DFT functional employed, the interaction strength decreased in the order of PBE+D > M06-2X > M05-2X. A common feature for the geometry of all four complexes considered, reproduced in all the calculations, is that HPc macrocycle undergoes strong distortion, which allows for increasing its contact surface with the nanotube sidewall or spherical fullerene, and therefore makes π-π interactions more efficient. [ABSTRACT FROM AUTHOR]

This study explains some electronic and structural parameters of niacin (NA) encapsulation into PAMAM-G1 dendrimer using DFT calculations. Optimized structural geometries, interaction energies, NMR, NBO, and AIM analyses, in accordance with experiment, revealed that the stability of G1@NA complex can be attributed to the five intermolecular hydrogen bonds formed between the functional groups of G1 and NA. Because of nearing to the experimental results, all the calculations repeated again using a self-consistent reaction field (SCRF) and the polarizable continuum model (PCM) to address the implicit solvent effects and the obtained results were in line with the calculations in gas phase. [ABSTRACT FROM AUTHOR]

Two kinds of structures are identified for the [CH 2 XNO 2 ·H 2 O] (X = H, F, Cl, Br, I) clusters, using ab initio and DFT computational techniques. The configurations of the resulting water complexes arise from the two different ways of possible hydrogen bonding interaction. Both types of complexes present cyclic geometries formed through either the interaction of a methylic H with the O atom of the water molecule, type (a), or via the symmetric coupling of each H atom of the water molecule with each O atom of the nitro group, type (b). The examination of the stereochemistry of the complexes shows a dependence on the halogen atom involved. The type (a) complexes are more stable and assumingly, those are primarily involved in the degradation mechanism of halogenated nitromethanes in water solvated surroundings. [ABSTRACT FROM AUTHOR]

We calculate the CCSD(T)/CBS complexation energies of C 6 X 6 ⋯C 2 X n complexes (X = F, Cl; n = 2, 4) by means of the W1-F12 and CCSD(T)/MP2(CBS) procedures. These complexes involve π–π stacking, charge-transfer, and van der Waals interactions and their complexation energies range between 11.1 (C 6 F 6 ⋯C 2 F 2 ) and 34.0 (C 6 Cl 6 ⋯C 2 Cl 4 ) kJ mol − 1 . We use our best CCSD(T)/CBS data to assess the performance of DFT, double-hybrid DFT (DHDFT), and standard/composite ab initio methods. The G4 and G4(MP2) composite methods show relatively poor performance with root-mean-square deviations (RMSDs) of 8.7 and 6.3 kJ mol − 1 , respectively. With the main exception of the Minnesota functionals, DFT functionals without a dispersion correction do not predict binding in these complexes. Most of the conventional DFT procedures attain RMSDs above the ‘chemical accuracy’ threshold. The best performing functionals with RMSDs ≤2.0 kJ mol − 1 are: B3LYP-D3, PW6B95-D3, LC-ωPBE-D3, PWPB95-D3, B2GP-PLYP-D3, and B2-PLYP-D3. [ABSTRACT FROM AUTHOR]

The isolation of reaction products of asparagine with reducing sugars at alkaline pH and high temperature has been probed by a combination of high performance liquid chromatography (HPLC) coupled with a Fraction Collector. The UV–vis and FTIR spectra of the isolated Maillard reaction products showed structure-sensitive changes as depicted by deamination events and formation of asparagine-saccharide conjugates. The initial reaction species of the Asn-Gluc reaction were also characterized by Density Functional Theory (DFT) methods. Evidence for Cu (II) metal ion complexation with the Maillard reaction products is supported by UV–vis and FTIR spectroscopy. [ABSTRACT FROM AUTHOR]

We performed a systematic comparative theoretical study of noncovalent interactions of free-base H2Pc and a series of 3d transition metal(II) phthalocyanines (where the transition metals included manganese, iron, cobalt, nickel, copper and zinc) with fullerene C60, by employing a DFT technique accounting for vdW interactions (PBE GGA functional with a dispersion correction by Grimme). We observed four different types of Pc interaction with fullerene cage, depending on central metal atom. Upon complexation with C60, the macrocyclic plane undergoes distortion in all cases, to a different degree. Some correlation was observed between the calculated formation energies for Pc'fullerene complexes and intermolecular separations in them, where stronger binding is generally associated with shorter M. . .CC60 and N. . . CC60 distances. Despite of considerable differences in the structure of Pc-fullerene complexes, the latter do not exhibit notable variations in the distribution of electrostatic potential, contrary to spin density plots for open-shell species. Similarly, HOMO and LUMO distribution can vary within some limits. [ABSTRACT FROM AUTHOR]

High level theoretical calculations were employed to study the structural and conformational equilibrium of the Oxacalix[4]arenes. We have proposed that the replacement of methylene bridges with the oxygen atoms stabilizes 1,3-Alternate conformer predominantly. Furthermore, assessment of conformational equilibrium was explored in gaseous as well as solvation phases. The role of dispersion forces, possibility of complexation, distribution of electrostatic-potential, population analysis, substitution effects that are crucial for the analyte recognition were also discussed. [ABSTRACT FROM AUTHOR]

The anion binding selectivity and the recognition mechanism of two isomeric boranes, namely, 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([p-(Mes2B)C6H4(NMe3)]+, 1, where "Mes" represents mesitylene and "Me" represents methyl) and 2-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([o-(Mes2B)C6H4(NMe3)]+, 2) has been investigated using density functional theory (DFT) and time dependent-density functional theory (TD-DFT) methods. Natural population analysis indicates that the central boron atoms in 1 and 2 are the most active centers for nucleophilic addition of anions. The negative magnitude of free energy changes (ΔG) reveals that out of CN-, F-, Cl-, Br-, NO3 -, and HSO4 - only the binding of CN- and F- with 1 and 2 is thermodynamically feasible and spontaneous. In addition, the calculated binding energies reveal that the CN- is showing lesser binding affinity than F- both with 1 and 2, while other ions, viz. NO3 -, HSO4 -, Br-, and Cl-, either do not bind at all or show very insignificant binding energy. The first excited states (S1) of 1 and 2 are shown to be the local excited states with π → σ* transition by frontier molecular orbital analysis, whereas fourth excited states (S4) of 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline cyanide ([p-(Mes2B)C6H4(NMe3)] CN, 1CN, the cyano form of 1) and 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline fluoride ([p-(Mes2B)C6H4(NMe3)] F, 1F, the fluoro form of 1) and fifth excited state (S5) of 2-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline fluoride ([o-(Mes2B)C6H4(NMe3)] F, 2F, the fluoro form of 2) are charge separation states that are found to be responsible for the intramolecular charge transfer (ICT) process. The synergistic effect of ICT and partial configuration changes induce fluorescence quenching in 1CN, 1F, and 2F after a significant internal conversion (IC) from S4 and S5 to S1. [ABSTRACT FROM AUTHOR]

The synthesis of 2-substituted pyridine-pyrimidine ligands and their complexation with arene ruthenium(II) chloride moieties is reported. Depending on the electronic and steric influences of the ligand, the catalysts undergo CH activation by roll-over cyclometalation. This process opens up the route to the catalytic transfer hydrogenation of ketones with isopropanol as the hydrogen source under base-free and mild conditions. Barriers related to the roll-over cyclometalation process can be determined experimentally by collision-induced dissociation ESI mass spectrometry. They are supported by DFT calculations and allow the classification of the ligands according to their electronic and steric properties, which is also in accordance with critical bond parameters derived from X-ray structure data. DFT calculations furthermore reveal that the formation of a ruthenium(II) hydrido species is plausible through β-hydride elimination from isopropanol. [ABSTRACT FROM AUTHOR]

Structurally modified CMPO functionalized pillar[5]arenes in ionic liquid were found to be highly efficient, and radiolytically stable systems for the selective separation of thorium. The extraction was demonstrated to proceed via ‘cation exchange’ mechanism through [Th.L (NO 3 )] 3 + species while the DFT calculation was used for understanding the optimized ligand structure and its complexation with Th 4 + ion in ionic liquid. Oxalic acid was found to be successful for almost quantitative back extraction of thorium from CMPO functionalized pillar[5]arene complex in ionic liquid. [ABSTRACT FROM AUTHOR]

The novel 3D hollow Sb 2 S 3 /S@S-doped carbon composite were prepared based on coupling reaction and superior electrochemical performance was achieved. [Display omitted] • Sb 2 S 3 /S@S-doped carbon composite with a hollow core–shell structure is synthesized. • The structure is prepared based on template method and coupling reaction. • S/S-doped carbon can interact with Sb 2 S 3 to improve the reactivity with Na+. • The as-prepared composite electrode displays superior sodium storage performance. Although the high-capacity Sb 2 S 3 -based anode materials for sodium-ion batteries can combine the advantages of multi-step conversion of Sb 2 S 3 to Sb and alloying reaction between Sb and Na for improving the performance, the slow reaction kinetics, low electronic conductivity, and poor reversibility of the sodium storage process have limited their practical application. To effectively improve the electrochemical performance, a three-dimensional Sb 2 S 3 /S@S-doped carbon composite with a hollow core–shell structure based on the combination of template method and coupling reaction is successfully synthesized. By combining the finite element simulation, dynamic analysis, and density functional theory calculation, the respective roles of S-composite and hollow core–shell structure in boosting performance are revealed. The internal S and external S-doped carbon can interact with Sb 2 S 3 to improve its reactivity with Na+, and effectively release the stress of Sb 2 S 3 in the sodiation process. The S-doped carbon can accelerate Na+ diffusion and further stabilize the structure of Sb 2 S 3. Benefited from the special structure, the as-prepared anode displays high reversible capacity, superior cycle performance and high rate capability. The assembled full battery also exhibits an excellent energy density under high power, and can still maintain a high reversible capacity of 310 mAh/g at 1 A/g over 500 cycles. [ABSTRACT FROM AUTHOR]

Water/ethanol complexation inducing solubility variation of transition-metal p -toluenesulfonates (tosylates) was investigated. The solubilities of hexaquocobalt(II) bis ( p -toluenesulfonate) [Co(OTs) 2 ·6H 2 O] and hexaquonickel(II) bis ( p -toluenesulfonate) [Ni(OTs) 2 ·6H 2 O] in water/ethanol mixtures were measured at T = 298.15 K. All the experimental data were well-correlated by the (CNIBS)/Redlich-Kister model. A distinct variation phenomenon of solubility was observed when the mole fraction of ethanol ( x 0 ) changed from 0.000–1.000. Based on the experimental data, two kinds of possible water/ethanol clusters [(water) 2 -ethanol and water-(ethanol) 3 ] were proposed, and five special values of x 0 ( x 0,1 − x 0,5 ) were obtained by a mathematical study of the (CNIBS)/Redlich-Kister model. The interactions of hydrogen bonds between tosylates and water (or ethanol, water/ethanol clusters) were calculated by Materials Studio DMol 3 . The formation and change of the above clusters at special values of x 0 were analyzed, based on which, the variation of solubility induced by water/ethanol complexation was investigated. [ABSTRACT FROM AUTHOR]

The nondestructive reversible complexation of the macrocyclic group 11 metal pyrazolates {[3,5-(CF3)2Pz]M}3 (M = Cu(I), Ag(I)) to the halogen atom X = Cl, Br of η³-allyliron tricarbonyl halides (η³-2-R-C3H4)Fe(CO)3X is revealed by the variable-temperature spectroscopic (IR, NMR) study combined with density functional theory calculations. The composition of all complexes at room temperature is determined as 1:1. In the case of the [AgL]3 macrocycle, complexes 1:2 are observed at low temperature (<260 K). The complex's stability depends on the substituents in the allyl fragment and halide ligand as well as on the metal atom (Ag(I), Cu(I)) in the macrocycle. For bulky substituents (Me and Ph) the endo/exo equilibrium of the parent (η³-2-R-C3H4)Fe(CO)3X shifts upon the complex formation in favor of the exo isomer due to additional noncovalent interactions of the substituent with macrocycle. [ABSTRACT FROM AUTHOR]

Complexation of two 1,3-alternate calix[4]crown ligands with alkali metals (K + , Rb + and Cs + ) has been investigated by electrospray ionization mass spectrometry (ESI-MS) and density functional theory calculations. The binding selectivities of the ligands and the binding constants of their complexes in solution have been determined using the obtained mass spectra. Also the percentage of each formed complex species in the mixture of each ligand and alkali metal has been experimentally evaluated. For both calix[4]crown-5 and calix[4]crown-6 ligands the experimental and theoretical selectivity of their alkali metal complexes found to follow the trend K + > Rb + > Cs + . The structures of ligands were optimized by DFT-B3LYP/6-31G method and the structures of complexes were obtained by QM-SCF-MO/PM6 method and discussed in the text. [ABSTRACT FROM AUTHOR]

Amidoxime-based polyethylene fiber plays an important role in sequestering uranium from seawater. Co-grafting carboxyl groups with amidoxime onto polyethylene fibers can enhance the uranium sorption efficiency. This work aims to theoretically understand the complexation of uranyl with amidoxime-, carboxyl- and mixed amidoxime/carboxyl-based host architectures within a polyethylene fiber. Using density functional theory method, we examined the geometrical structures, the electronic structures and the thermodynamic stabilities of various substitution complexes, as well as the effect of host structure on these complexes. The results showed that the affinity of amidoximate (AO − ) for uranyl is similar to that of CO 3 2− , but stronger than that of carboxyl (AA − ). For the uranyl complexes with separate mixed amidoximate/carboxyl, the U–O(AO − ), U–N(AO − ) and U–O(AA − ) bonds show the decreasing order of covalent character. However, for the uranyl complexes with mixed amidoximate/carboxyl-based host architectures, the covalent character of U–O(AO − ), U–O(AA − ) and U–N(AO − ) bonds decrease in sequence. HAA is thermodynamically more favorable to react with UO 2 (CO 3 ) 3 4− forming a complex than HAO, which is due to the higher dissociation ability of HAA compared to HAO. The dissociated H + from HAA is conducive for the dissociation of UO 2 (CO 3 ) 3 4− , which is possibly the origin of the synergistic effects between HAO and HAA in the uranium extraction process from seawater. The host structures have a strong impact on the interaction between uranyl and the amidoxime-, carboxyl- and mixed amidoxime/carboxyl-based host architectures. Comparing all the host architectures, those with –(CH 2 ) 4 – and –(CH 2 ) 3 – as linkages are more appropriate for uranyl together with one CO 3 2− group. [ABSTRACT FROM AUTHOR]

An N-pivot diglycolamide extractant (DGA-TREN) was synthesized for the first time and its complexation behaviour was studied towards trivalent lanthanide/actinide ions. The solvent extraction studies suggested a unique selectivity reversal in the extraction of trivalent actinides versus trivalent lanthanides which was observed performing extraction studies in an ionic liquid vis-à-vis a molecular diluent for a tripodal TREN-based diglycolamide ligand (DGA-TREN) vs. a tripodal diglycolamide ligand (T-DGA) which may have great significance in radioactive waste remediation. The nature of the bonding to Eu3+ ion was investigated by EXAFS as well as by DFT calculations. [ABSTRACT FROM AUTHOR]

The co-adsorption of O2 and CO on anionic sites of gold species is considered as a crucial step in the catalytic CO oxidation on gold catalysts. In this regard, the [Au2O2(CO) n]− ( n=2-6) complexes were prepared by using a laser vaporization supersonic ion source and were studied by using infrared photodissociation spectroscopy in the gas phase. All the [Au2O2(CO) n]− ( n=2-6) complexes were characterized to have a core structure involving one CO and one O2 molecule co-adsorbed on Au2− with the other CO molecules physically tagged around. The CO stretching frequency of the [Au2O2(CO)]− core ion is observed around [ABSTRACT FROM AUTHOR]

We have employed density functional theory to study and characterize a new family of belt shaped molecules which use the norbornadiene tether and aromatic molecules as linkers. Our results indicated that the inclusion of the norbornadiene unit eliminates the strain commonly associated with the synthesis of belt-shaped molecules. Polymerization of the latter proved to be an effective method towards the bottom-up synthesis of organic nanotubes with uniform properties. The band gap of the infinite nanotubes proposed can be engineered by changing the molecule which links the norbornadiene tethers. In effect, the gap of the pyrene/norbornadiene and coronene/norbornadiene based nanotubes were 2.9 eV and 0.9 eV, respectively, as indicated by HSE calculations. Among the six belts assayed, two can be used to separate the magic fullerenes C180and C240, given that large interaction energies were found upon complexation. [ABSTRACT FROM AUTHOR]

The novel phosphonyl-substituted ferrocene derivatives [Fe(η5-Cp)(η5-C5H3{P(O)(O- iPr)2}2-1,2)] ( Fc1,2) and [Fe{η5-C5H4P(O)(O- iPr)2}2] ( Fc1,1′) react with SnCl2, SnCl4, and SnPh2Cl2, giving the corresponding complexes [(Fc1,2)2SnCl][SnCl3] ( 1), [{(Fc1,1′)SnCl2} n] ( 2), [(Fc1,1′)SnCl4] ( 3), [{(Fc1,1′)SnPh2Cl2} n] ( 4), and [(Fc1,2)SnCl4] ( 5), respectively. The compounds are characterized by elemental analyses, 1H, 13C, 31P, 119Sn NMR and IR spectroscopy, 31P and 119Sn CP-MAS NMR spectroscopy, cyclovoltammetry, electrospray ionization mass spectrometry, and single-crystal as well as powder X-ray diffraction analyses. The experimental work is accompanied by DFT calculations, which help to shed light on the origin for the different reaction behavior of Fc1,1′ and Fc1,2 towards tin(II) chloride. [ABSTRACT FROM AUTHOR]

On the basis of extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Tl+(aq) +1·Cs+(nb)1·Tl+(nb) + Cs+(aq) taking place in the two-phase water–nitrobenzene system (1= calix[4]arene-(2,3-naphthylene-crown-6,crown-6); aq = aqueous phase, nb = nitrobenzene phase) was determined as logKex(Tl+,1·Cs+) = 0.3 ± 0.1. Further, the extremely high stability constant of the1·Tl+complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log βnb(1·Tl+) = 10.0 ± 0.2. Finally, applying quantum mechanical calculations, the most probable structure of the cationic complex species1·Tl+was derived. In the resulting complex, the ‘central’ cation Tl+is bound by eight strong bonds to six oxygen atoms of the crown-6 moiety and to two carbons from the respective two benzene rings of the parent ligand1via cation-π interaction. The interaction energy,E(int), of the considered1·Tl+complex was found to be −305.7 kJ/mol, also confirming the formation of this cationic species. [ABSTRACT FROM AUTHOR]

Complexation of NpO2+ ions with glutaroimide dioxime (H2L), a cyclic imide dioxime ligand that has been shown to form strong complexes with UO22+ in aqueous solutions, was studied by absorption spectroscopy and microcalorimetry in 1.0 M NaClO4 aqueous solutions. NpO2+ forms two successive complexes, NpO2(HL)(aq) and NpO2(HL)2- (where HL- stands for the partially deprotonated glutaroimide dioxime ligand), with stability constants of log β111 = 17.8 ± 0.1 and log β122 = 33.0 ± 0.2, respectively. The complexation is both enthalpy- and entropy-driven, with negative enthalpies (ΔH111 = −52.3 ± 1.0 kJ/mol and ΔH122 = −96.1 ± 1.4 kJ/mol) and positive entropies (ΔS111 = 164 ± 3 J/mol/K and ΔS122 = 310 ± 4 J/mol/K). The thermodynamic parameters suggest that, similar to complexation of UO22+, the ligand coordinates with NpO2+ in a tridentate mode, via the two oxygen atoms of the oxime groups and the nitrogen atom of the imide group. Density functional theory calculations have helped to interpret the optical absorption properties of the NpO2(HL)2- complex, by showing that the cis and trans configurations of the complex have very similar energies so that both configurations could be present in the aqueous solutions. It is the noncentrosymmetric cis configuration that makes the 5f → 5f transition allowable so that the NpO2(HL)2- complex absorbs in the near-IR region. [ABSTRACT FROM AUTHOR]

We performed a theoretical investigation for the selectivity of Eu(III)/Am(III) ions depending on the donor atoms by means of all-electron ZORA-DFT calculation. We estimated their selectivity as the relative stability in the complex formation reaction. The B2PLYP functional reproduced the experimental selectivity in which S- and N-donor ligands favor Am(III) ion, but O-donor ligand favors Eu(III) ion. Mulliken's bond overlap population analysis revealed that the contribution of the f orbital to the bonding was small or zero for Eu complex, whereas it was large for Am complex. The bonding nature of the f orbital for Am ion was the bonding type to S- and N-donor ligands, while it was the antibonding type to O-donor ligand. It was suggested that the difference in the bonding nature between the f orbital in the metal and the donor atoms determines the selectivity of Eu(III)/Am(III) by donor ligands. [ABSTRACT FROM AUTHOR]

To examine the effects of different functionalization methods on adsorption behavior, anionic-exchange MIL-101(Cr) metal-organic frameworks (MOFs) were synthesized using preassembled modification (PAM) and postsynthetic modification (PSM) methods. Perfluorooctanoic acid (PFOA) adsorption results indicated that the maximum PFOA adsorption capacity was 1.19 and 1.89 mmol g-1 for anionic-exchange MIL-101(Cr) prepared by PAM and PSM, respectively. The sorption equilibrium was rapidly reached within 60 min. Our results indicated that PSM is a better modification technique for introducing functional groups onto MOFs for adsorptive removal because PAM places functional groups onto the aperture of the nanopore, which hinders the entrance of organic contaminants. Our experimental results and the results of complementary density functional theory calculations revealed that in addition to the anion-exchange mechanism, the major PFOA adsorption mechanism is a combination of Lewis acid/base complexation between PFOA and Cr(III) and electrostatic interaction between PFOA and the protonated carboxyl groups of the bdc (terephthalic acid) linker. [ABSTRACT FROM AUTHOR]

Despite the fact that the complexation of ammonium cations with ionophores like crown ethers plays an important role in biological and industrial processes, there is still a lack of theoretical methods to reproduce or even predict the host-guest complex structures or their thermodynamic stabilities in an accurate manner. Hence, the development of ionophores has often relied on a trial-and-error approach and the synthetic efforts associated with this have been enormous, so far. Therefore, theoretical methods for the reliable prediction of binding affinities of crown ether derivatives with ammonium ions would be an indispensable tool for the rational design of new receptors with tailored properties. Here, we suggest a computationally efficient but still accurate theoretical approach. It is tested for a model system consisting of 18-crown-6 ether and an ammonium cation, but is invented for application to much larger complexes. The accuracy of various approximate quantum-chemical methods, based on density functional theory (DFT) and many-body perturbation theory, is evaluated against the gold standard CCSD(T) in the basis set limit as internal reference. An important aspect is the consideration of dispersion interactions in DFT methods, for which the dispersion-correction by Grimme was employed. For all selected methods, the basis-set dependence of calculated interaction energies was investigated. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The Fourier transform IR and Raman spectra of the zero generation dendrimer G 1 with two P N P S linkages and four terminal aldehyde groups have been recorded. The optimized geometry of low energy isomer of G 1 have been calculated by density functional (DFT) method at the PBE/TZ2P level of theory. DFT is used for analyzing the properties of P N P S linkages. DFT results for the structure of G 1 are in good agreement with X-ray diffraction measurements. A complete vibrational assignment is proposed for different parts of G 1 . The global and local reactivity descriptors have been used to characterize the reactivity pattern of the core function and terminal group. Natural bond orbital (NBO) analysis has been applied to comparative study of charge delocalization. Our study reveals that the softness and electrophilicity of sulfur atom in the core of the dendrimer G 1 is higher than that of sulfur atoms and of the dendron G 2 . Thus P N P S linkage has a high electron density on sulfur which allows the regiospecific complexation of gold, whereas the other P S groups do not react this way. This explains why P N bond in P N P S linkage is much more stable than isolated P N bonds, which are easily hydrolyzed. [ABSTRACT FROM AUTHOR]

Benchmark calculations of 15 N NMR shielding constants for a set of model complexes of rhodium(II) tetraformate with nine organic ligands using the Density Functional Theory (DFT) methods have been carried out. The calculations were performed by means of several methods: the non-relativistic, relativistic scalar ZORA, and spin-orbit ZORA approaches at the CGA-PBE/QZ4P theory level, and the GIAO NMR method using the B3PW91 functional with the 6-311++G(2d,p) basis set for C, H, N, O atoms and the Stuttgart basis set for the Rh atom. The geometry of compounds was optimised either by the same basis set as for the NMR calculations or applying the B3LYP functional with the 6-31G(2d) basis set for C, H, N, O atoms and LANL2DZ for the Rh atom. Computed 15 N NMR shielding constants σ were compatible with experimental 15 N chemical shifts δ of complexes exhibiting similar structure and fulfil the linear equation δ = aσ + b . The a and b parameters for all data sets have been estimated by means of linear regression analysis. In contrast to the correlation method giving “scaled” chemical shifts, the conversion of shielding constants to chemical shifts with respect to the reference shielding of CH 3 NO 2 provided very inaccurate “raw” δ values. The application of the former to the calculation of complexation shifts Δ δ (Δ δ = δ compl − δ lig ) reproduced experimental values qualitatively or semi-quantitatively. The non-relativistic B3PW91/[6-311++G(2d,p), Stuttgart] theory level reproduced the NMR parameters as good as the more expensive relativistic CGA-PBE//QZ4P ZORA approaches. [ABSTRACT FROM AUTHOR]

Theoretical calculations (density functional theory with the scalar relativistic ZORA Hamiltonian) have been performed to obtain the energy and Gibbs free energy of formation of cationic 1 : 3 complexes of americium(iii) and europium(iii) with a tri-O-dentate diglycolamide ligand TEDGA (a model of TODGA extractant), as well as the free energy of their partition between water and an organic diluent. The distribution of electron density over the atoms, bonds, and molecular orbitals was analyzed by means of Mulliken population analysis, the localization procedure of natural bond orbitals, and the Quantum Theory of Atoms-in-Molecules. The stabilities of both [M(TEDGA)3]3+ complexes are similar to each other. On the other hand, our recent data for a similar pair of cationic Am/Eu complexes with a softer (HSAB) tetra-N-dentate ligand C2-BTBP show that the [Am(C2-BTBP)2]3+ complex is significantly more stable in aqueous solution than its Eu counterpart. The decisive factor stabilizing the Am3+ complexes over their Eu3+ analogues is the charge transfer from the ligands, somewhat greater on the 6d(AmIII) than on 5d(EuIII) orbitals. The covalency of M–N bonds in the [M(C2-BTBP)2]3+ complexes is greater than that of M–O bonds in [M(TEDGA)3]3+, but the latter is not negligible, in particular in the bonds with the oxygen atoms of the amide groups in TEDGA. The analysis of charge distribution over the whole molecules of the complexes shows that the TEDGA molecule is not hard as expected, but a relatively soft Lewis base, only slightly harder than BTBP. This conclusion has been confirmed by the calculation of the chemical hardness of the ligands. Moreover, the comparison of the results of bonding analysis with the calculated energies of complex formation in water and in the gas phase allows us to conclude that the population analysis, QTAIM topological parameters, and SOPT stabilization energy, as well as Wiberg and overlap-weighted NAO indices are the tools for analyzing the covalency rather than the total bond strength. [ABSTRACT FROM AUTHOR]

The acid-base properties of the thiourea based cyclic thiosemicarbazone have been studied. The tautomerism and complex formation ability of the thiosemicarbazone were investigated by the methods of quantum chemistry and electronic spectroscopy. The complexes of copper(II), nickel(II), cobalt(II), and mercury(II) were synthesized and their structure suggested. [ABSTRACT FROM AUTHOR]

The equimolar complexation behavior of urea or thiourea with 2-alcoxybenzamides has been studied by theoretical calculations. Structural models for the calculation were constructed from the X-ray crystallographic structures of 2-methoxybenzamide (MB) crystal and 2-ethoxybenzamide (EB)-thiourea, MB-thiourea, and MB-urea equimolar cocrystals. Structural optimization for EB-urea equimolar cocrystal was performed by the density functional theory (DFT) method (B3LYP/6-31G** level) and the complexation energy was determined using the DFT with higher order basis set (6-31+G**). Energetic stabilization by the equimolar complexation was observed in the three equimolar complexes. The reason why the amide group of MB is out-of-plane in unprocessed MB crystals is well explained by the calculations. It was suggested that intermolecular hydrogen bonding increases in the out-of-plane structure of MB and that subsequently leads to stabilization in the crystal. The amide group of MB or EB was inplane by the complex formation with urea or thiourea. Finally, we predict the possibility of EB-urea equimolar complex formation in terms of the complexation energy. [ABSTRACT FROM AUTHOR]

A new naphthalene-containing macrocyclic triazole ( 1 ) and its acyclic compared compound ( 2 ) have been synthesized and characterized. In acetonitrile and acetonitrile aqueous solutions, 1 and 2 showed good fluorescence sensing ability to Hg 2+ over other metal ions, with 1 exhibiting better sensitivity and selectivity than 2 owing to its macrocyclic effect. 1 H NMR titrations and DFT calculation results showed that the N atoms of triazole and O atoms of the ether groups in 1 and 2 participate in binding during complexation with Hg 2+ . [ABSTRACT FROM AUTHOR]

Highlights: [•] Present work highlighted on designed synthesis of a Schiff-base PyMD for fluorescence based detection of zinc metal ion. [•] UV–vis, fluorescence, life time analysis, 1H NMR titration and HRMS analysis confirm 1:1 complex formation. [•] DFT was also employed for theoretical affirmation of experimental findings regarding metal–ligand complexation. [•] This ligand was successfully used for quantification of zinc ion in some real natural samples. [Copyright &y& Elsevier]

In order to develop a new class of transition-metal-based, two-stage photobase generators (PBGs), the synthesis, structural characterization, spectroscopic properties and base-generation ability of a series of [CpRu(η 6 -benzylcarbamate)]X salts (X = [PF 6 ] − , [O 3 SCF 3 ] − ) are reported. Treatment of [CpRu(NCMe) 3 ]PF 6 with the N , N -dialkylcarbamate PBGs 2-nitrophenylmethyl N , N -dicyclohexylcarbamate (2NC), 4-nitrophenylmethyl N , N -dicyclohexylcarbamate (4NC) and 3,5-dimethoxyphenylmethyl N , N -dicyclohexylcarbamate (DMC) results in η 6 -complexation of the arene fragment and formation of the corresponding [CpRu(η 6 -benzylcarbamate)]PF 6 salt. The [PF 6 ] − salt, [CpRu(η 6 -DMC)]PF 6 , is converted to the triflate salt (triflate = [O 3 SCF 3 ] − = [OTf] − ) by treatment with Me 3 SiOTf. The molecular structures of the [CpRu(η 6 -benzylcarbamate)]X salts were determined by X-ray diffraction and varied by the orientation of the carbmamate unit relative to the η 5 -Cp ligand. Experimental UV–Vis data and Time-Dependent DFT calculations suggest that the [CpRu(η 6 -benzylcarbamate)] + cations possess high-energy excitations that potentially render these salts as useful two-stage PBGs. The photobase generation ability of the [CpRu(η 6 -benzylcarbamate)]X salts at 254 nm irradiation is assessed in both acetonitrile solution and polymethacrylate thin films. The irradiation studies demonstrate that η 6 -coordination of a benzylcarbamate PBG does not deactivate photolytic base generation. [ABSTRACT FROM AUTHOR]

The complexation properties of Am(III) and Eu(III) with a serial of novel N-heterocyclic tetradentate ligands, 2,9-bis(dialkyl-1,2,4-triazin-3-yl)-1,10-phenanth-rolines (BTPhens), have been calculated by density functional theory (DFT) coupled with relativistic small-core pseudopotential. It is found that the nitrogen atoms in triazine rings favor metal cations more than those in phenanthroline skeleton. The Am-N bond lengths are comparable to or even shorter than those of Eu-N bonds based on the larger radii of Am(III) than Eu(III). The effect of alkyl substituents on the complex structures is limited but they can adjust the complexation reaction and extraction kinetics. Additionally, the solvent effect can decrease the probability of the complexation reactions greatly and the solvation energies of Am(III) and Eu(III) might be the primary driving force in the complexation selectivity. The complexation reactions for forming ML(NO3)3 and [ML2(NO3)]2+ complexes are believed to dominate the selective extraction separation of Am(III) from Eu(III) in nitric acid media, which agrees well with the experimental results. The comparisons of BTPhens with BTBPs in dipoles and electronic structures confirm that the BTPhens exhibit more favourable extraction kinetics and selectivity for minor actinides. [ABSTRACT FROM AUTHOR]