Showing papers in "New Journal of Chemistry in 2009"
TL;DR: The unusual magnetism exhibited by dysprosium triangles [Dy3(μ3-OH)2L3Cl2(H2O)4] is explained using the recently developed ab initio methodology for the simulation of magnetic properties of complexes as mentioned in this paper.
Abstract: The unusual magnetism exhibited by dysprosium triangles [Dy3(μ3-OH)2L3Cl2(H2O)4][Dy3(μ3-OH)2L3Cl(H2O)5]Cl5·19H2O is explained using the recently developed ab initio methodology for the simulation of magnetic properties of complexes The local anisotropy axes on the dysprosium sites are found to lie in the plane of the Dy3 triangle and to make angles of ca 120° with each other The small antiferromagnetic exchange interaction between sites leads to a non-magnetic Kramers doublet in the ground state of the complex The arrangement of the local magnetization vectors in this state is close to toroidal By contrast, the lowest excited states are characterized by a huge magnetic moments of ca 20 μB and show very different behavior of magnetization for fields applied along and perpendicular to the plane of the Dy3 triangle
305 citations
TL;DR: The contribution of dendrimers to the field of nanomedicine is discussed in this article, focusing on the extraordinary possibilities offered by their multivalent and defined structure, as well as the underlying concepts that make Dendrimeric systems so attractive.
Abstract: What is the contribution of dendrimers to the field of nanomedicine? Rather than disclosing an exhaustive catalogue of their possible applications, this review article sets a putative answer by showing the basics and the underlying concepts that make dendrimeric systems so attractive to nanomedicine, emphasizing on the extraordinary possibilities offered by their multivalent and defined structure.
176 citations
TL;DR: The dual nature of ionic liquids has been exploited to synthesize materials that contain two independent biological functions by combining anti-bacterial quaternary ammonium compounds with artificial sweetener anions as discussed by the authors.
Abstract: The dual nature of ionic liquids has been exploited to synthesize materials that contain two independent biological functions by combining anti-bacterial quaternary ammonium compounds with artificial sweetener anions. The synthesis and physical properties of eight new ionic liquids, didecyldimethylammonium saccharinate ([DDA][Sac]), didecyldimethylammonium acesulfamate ([DDA][Ace]), benzalkonium saccharinate ([BA][Sac]), benzalkonium acesulfamate ([BA][Ace]), hexadecylpyridinium saccharinate ([HEX][Sac]), hexadecylpyridinium acesulfamate ([HEX][Ace]), 3-hydroxy-1-octyloxymethylpyridinium saccharinate ([1-(OctOMe)-3-OH-Py][Sac]), and 3-hydroxy-1-octyloxymethylpyridinium acesulfamate ([1-(OctOMe)-3-OH-Py][Ace]), are reported, as well as the single crystal structures for [HEX][Ace] and [1-(OctOMe)-3-OH-Py][Sac]. Determination of anti-microbial activities is described for six of the ILs. While some exhibited decreased anti-microbial activity others showed a dramatic increase. For two of the ionic liquids, [DDA][Sac] and [DDA][ACE], oral toxicity, skin irritation, and deterrent activity was also established. Unfortunately, both ILs received a Category 4 (harmful) rating for oral toxicity and skin irritation. However, deterrent activity experiments point to use as an insect deterrent, as both ILs scored either “very good” or “good” against several types of insects.
173 citations
TL;DR: In this paper, N-Heterocyclic carbene coated Au and Pd nanoparticles have been prepared by a ligand exchange reaction; although carbenes quantitatively displaced the thioether and phosphine ligands from the nanoparticle surface, the resultant nanoparticles spontaneously leached metal complexes and aggregated in solution.
Abstract: N-Heterocyclic carbene coated Au and Pd nanoparticles have been prepared by a ligand exchange reaction; although carbenes quantitatively displaced the thioether and phosphine ligands from the nanoparticle surface, the resultant nanoparticles spontaneously leached metal complexes and aggregated in solution.
143 citations
TL;DR: The photophysical and spectroscopic characterization of four new dimeric bis(BF2)-2,2′-bidipyrrins (BisBODIPYs) recently synthesized and characterized (Chem Eur J, 2008, 14, 2976-2983) has been undertaken along with that of the component BODIPy monomers as discussed by the authors.
Abstract: The photophysical and spectroscopic characterization of four new dimeric bis(BF2)-2,2′-bidipyrrins (BisBODIPYs) recently synthesized and characterized (Chem Eur J, 2008, 14, 2976–2983) has been undertaken along with that of the component BODIPY monomers The monomers display the typical photophysical properties of this family; (i) narrow and intense single absorption band in the visible range at 530 nm; (ii) intense, solvent independent emission (Φflca 1); (iii) narrow emission band with a 200–400 cm−1 Stokes shifted emission, independent of solvent polarity; (iv) no absorption features for the singlet excited state; (v) very little triplet yield and no ability to sensitize singlet oxygen The absorption spectra of the corresponding new dimers exhibit split band maxima in the visible range at about 490 and 560 nm, corresponding to an exciton splitting of ca 2600 cm−1 The luminescence in toluene is strong (Φflca 07, τ =34 ns), broad and Stokes shifted by ca 2200 cm−1, but both luminescence yield and Stokes shift are solvent polarity dependent; Φfl < 01, τ < 1 ns and the Stokes shift is close to 2700 cm−1 in acetonitrile Solvent viscosity does not appear to play an important role and freezing of the solvents to 77 K in a solid matrix cancels the differences in luminescence parameters Singlet and triplet excited state absorbance was measured in toluene and acetonitrile and the ability of these new dyes to sensitize singlet oxygen was examined The nature and dynamics of the excited state is discussed in comparison with the monomers properties and with some intra- or inter-molecular BODIPY dimers reported in the literature Potential applications of these new dyes with respect to BODIPYs are pointed out on the basis of their spectroscopic and photophysical properties
141 citations
TL;DR: In this paper, a detailed study of some environmentally friendly Mn(II) salts that form very efficient in situcatalysts for the activation of H2O2 in the oxidation of substrates such as Orange II under mild reaction conditions, was performed.
Abstract: In an effort to develop new routes for the clean oxidation of non-biodegradable organic dyes, a detailed study of some environmentally friendly Mn(II) salts that form very efficient in situcatalysts for the activation of H2O2 in the oxidation of substrates such as Orange II under mild reaction conditions, was performed. The studied systems have advantages from the viewpoint of green chemistry in that simple metal salts can be used as very efficient catalyst precursors and H2O2 is used as a green oxygen donor reagent. Oxidations were carried out in a glass reactor over a wide pH range in aqueous solution at room temperature. Under optimized conditions it was possible to degrade Orange II in a carbonate buffer solution in less then 100 s using 0.01 M H2O2 in the presence of only 2 × 10−5 M Mn(II) salt. To gain insight into the manganese catalyzed oxidation mechanism, the formation of the active catalyst was followed spectrophotometrically and appears to be the initiating step in the oxidative degradation of the dye. High valent manganese oxo species are instable in the absence of a stabilizing coordinating ligand and lead to a rapid formation of catalytically inactive MnO2. In this context, the role of the organic dye and HCO3− as potential stabilizing ligands was studied in detail. In situUV-Vis spectrophotometric measurements were performed to study the effect of pH and carbonate concentration of the buffer solution on the formation of the catalytically active species. Electrochemical measurements and DFT (B3LYP/LANL2DZp) calculations were used to study the in situ formation of the catalytic species. The catalytic cycle could be repeated several times and demonstrated an excellent stability of the catalytic species during the oxidation process. A mechanism that accounts for the experimental observations is proposed for the overall catalytic cycle.
112 citations
TL;DR: The production of a new class of glycolipid–metal nanoparticle conjugates, namely, sophorolipid reduced/capped silver nanoparticles is demonstrated for the first time, by unveiling the reducing and capping abilities of sophorlipid derived from oleic acid.
Abstract: The production of a new class of glycolipid–metal nanoparticle conjugates, namely, sophorolipid reduced/capped silver nanoparticles is demonstrated for the first time, by unveiling the reducing and capping abilities of sophorolipid derived from oleic acid. It is also demonstrated that the sophorolipid capped Ag nanoparticles are highly potent antibacterial agents, against both Gram-positive and Gram-negative bacteria. The utilization of sophorolipid brings out several advantages, such as eliminating the necessity for exogenous reducing agent and imparting better stability to the silver nanoparticles as compared to their oleic acid capped analogues. These sophorolipid capped silver nanoparticles can be obtained as a stable powder that can be re-dispersed in water as desired.
109 citations
TL;DR: In this paper, a series of thiophene-conjugated indoline dyes for zinc oxide solar cells, prepared by the one-step cathode deposition template method, was examined.
Abstract: The application of a series of thiophene-conjugated indoline dyes for zinc oxide solar cells, prepared by the one-step cathode deposition template method, was examined. The introduction of thiophene ring(s) into D131-type indoline dye improved the cell performance due to their appropriate energy levels and bathochromic shift in the UV-vis absorption band on zinc oxide. It is important for the oxidation potential (Eox) of dyes to have a more positive value than ca. 0.25 V vs. Fc/Fc+ in acetonitrile in order to show a high (>70%) incident photon-to-current efficiency.
109 citations
TL;DR: This short review focuses on advances in research for new complexes based on Pt(IV), Ru(II) and Ru(III) either as anticancer drugs or as molecular reagents for biomedical applications.
Abstract: Since the discovery of cisplatin, the search for therapeutic agents based on other metallic compounds developed rapidly thanks to the versatility of coordination chemistry. This short review focuses on advances in research for new complexes based on Pt(IV), Ru(II) and Ru(III) either as anticancer drugs or as molecular (photo)reagents for biomedical applications. The DNA binding mechanisms of these compounds are highlighted alongside with the novel strategies developed to improve their reactivity and/or specificity towards DNA.
96 citations
TL;DR: In this article, a superhydrophobic coating with an anti-corrosive property has been fabricated on aluminium foil by a simple sol-gel method with polystyrene spheres (PS) included as a removable template.
Abstract: A superhydrophobic coating with an anti-corrosive property has been fabricated on aluminium foil by a simple sol–gel method with polystyrene spheres (PS) included as a removable template. The effects of the size of PS on the surface structure and the superhydrophobicity have been researched. When the size of PS is 200 nm, the prepared coating shows a high static water contact angle (CA) larger than 150° but also a large adhesive force with the substrate, and the water droplet can be pinned on the substrate tilted at any angle. When the size of PS is 500 nm, the prepared coating has a CA as high as 160°, and the water droplet can roll off the substrate easily. Under this circumstance, the coated aluminium foil is also found to possess good chemical stability and, in particular, an anti-corrosive property. Thus the CA remains nearly unchanged after exposure to air for one year or immersion in an acid solution for 5 h.
92 citations
TL;DR: The asymmetry of the tetraalkylammonium cations is shown to have a significant influence on the viscosity of the ionic liquids composed of amino acid anions as discussed by the authors.
Abstract: Fifteen novel amino acid ionic liquids (AAILs) were prepared by the combination of several tetraalkylammonium cations with four amino acid anions ([Gly], [L-Ala], [β-Ala] and [Val]).The asymmetry of the tetraalkylammonium cations is shown to have a significant influence on the viscosity of the ionic liquids composed of amino acid anions, especially for the four triethylbutylammonium ([N2224])-based ionic liquids that have viscosities of lower than 60 mPa s, with the lowest being only 29 mPa s. The low viscosity tetraalkylammonium-based AAILs are further demonstrated to improve apparently the reaction and mass transfer rates of CO2 in the ionic liquids.
TL;DR: The goal of the organic, biological, or supramolecular chemist is to understand binding strength, binding dynamics, binding selectivity, transport selectivity and dynamics of chloride transporters.
Abstract: Chloride has emerged as one of the most vigorously studied ions that occur in nature. A continuing motivation for the study of chloride transport lies in the pathological conditions that relate to or involve chloride transport. The goal of the organic, biological, or supramolecular chemist, thus, is to understand binding strength, binding dynamics, binding selectivity, transport selectivity and dynamics of chloride transporters. Various successful anion transporters or channels are now known, although detailed characterization and elaboration in most cases is ongoing. Several of these synthetic systems will be discussed in this review as we focus our discussion on the efforts to develop artificial transporters for chloride anions.
TL;DR: Maya Blue, an ancient nanostructured organic-inorganic hybrid material resulting from the attachment of indigo, a natural dye, to a phyllosilicate clay, palygorskite, has received considerable attention of late as discussed by the authors.
Abstract: Maya Blue, an ancient nanostructured organic–inorganic hybrid material resulting from the attachment of indigo, a natural dye, to a phyllosilicate clay, palygorskite, has received considerable attention of late. Despite intensive research, several aspects remain unsolved, in particular the nature of the indigo–palygorskite association. Recent results suggest that the Maya Blue pigment is a complex system in which different topological isomers of various indigoid molecules attached to the palygorskite matrix coexist.
TL;DR: In this paper, 3 neutral compounds with high detonation velocities and excellent combined oxygen and nitrogen contents were synthesized starting from the corresponding 5amino-substituted tetrazoles in good yields and purities.
Abstract: 5-Nitro-2H-tetrazole (1), 1-methyl-5-nitrotetrazole (2) and 2-methyl-5-nitrotetrazole (3) were synthesized starting from the corresponding 5-amino-substituted tetrazoles in good yields and purities. The compounds were fully characterized by analytical and spectroscopic methods and their solid state structures were determined by low temperature X-ray diffraction techniques. Due to the potential of tetrazoles as energetic materials an extensive computational study (CBS-4M) was performed in order to estimate the energies of formation (ΔfU°) of the molecules, which are highly endothermic (1, 2527 kJ kg−1; 2, 2253 kJ kg−1 and 3, 2006 kJ kg−1). The EXPLO5 software was used to calculated the corresponding detonation velocities (Ddet) and detonation pressures (pdet) (1, Ddet = 9457 m s−1 and pdet = 390 kbar; 2, Ddet = 8085 m s−1 and pdet = 257 kbar and 3, Ddet = 8109 m s−1 and pdet = 262 kbar) by combining the ΔfU° values of the materials with the (X-ray calculated) densities and molecular formulas, giving performances comparable to commonly used secondary explosives (e.g., RDX). Lastly, all three neutral compounds can be easily initiated by impact (<2 J) and with high detonation velocities and excellent combined oxygen and nitrogen contents offer a more powerful and environmentally friendly alternative to commonly used primary explosives in initiating devices.
TL;DR: A new membrane-permeable Cu2+-selective water-soluble BODIPY 1, which was synthesized by nucleophilic disubstitution of novel 3,5-diiodo-BODIPy 4 with N,N-bis(2-hydroxyethyl)amines, shows a highly sensitive and selective fluorescence response to Cu2 + in aqueous solution.
Abstract: Copper ion is a biochemically essential yet toxic metal ion, connected to serious neurodegenerative diseases, and also has been identified as an environmental pollutant. For the effective detection of Cu2+ in biological and environmental systems, we have developed a new membrane-permeable Cu2+-selective water-soluble BODIPY 1, which was synthesized by nucleophilic disubstitution of novel 3,5-diiodo-BODIPY 4 with N,N-bis(2-hydroxyethyl)amines. BODIPY 1 shows a highly sensitive and selective fluorescence response to Cu2+ in aqueous solution. Fluorescence image experiments establish that 1 can be used to monitor intracellular Cu2+ within living cells.
TL;DR: In this article, Fe-tricarboxylate based metal-organic gels were modified with tert-butyl substituted or phosphine-functionalised gels in alcohols or DMF, which were subsequently functionalised with Pd(II)-immobilised gel and its xerogel/aerogel showed high activity in the catalysis of Suzuki C-C coupling comparable to unsupported complexes.
Abstract: Modification of Fe-tricarboxylate based metal–organic gels yielded tert-butyl substituted or phosphine-functionalised gels in alcohols or DMF, which were prepared from 5-tert-butylisophthalic acid and 5-diphenylphosphanylisophthalic acid, respectively. Owing to their permeability, such phosphine-functionalised metal–organic gels can act as a new type of functionalisable porous scaffold. The phosphorus-containing gel was subsequently functionalised with Pd(II) by immersion in a solution of Pd(COD)Cl2 (COD = 1,5-cyclooctadiene). The subsequently functionalised Pd(II)-immobilised gel and its xerogel/aerogel showed high activity in the catalysis of Suzuki C–C coupling comparable to unsupported complexes. The gel/xerogels could be reused under ambient atmosphere.
TL;DR: In this article, three chemosensors, DN1, DN2 and DN3, incorporating dansyl dye as a fluorophore and various carboxhydrazones as ionophores, are reported.
Abstract: Three chemosensors DN1, DN2 and DN3, incorporating dansyl dye as a fluorophore and various carboxhydrazones as ionophores, are reported. DN1 contains a pyridine-carboxhydrazone tridentate coordination site, forming a 2:1 stoichiometric complexation species with Cr3+, and exhibits selectivity for Cr3+ over alkali and alkaline earth metals and most first-row transition metals in aqueous media. DN1 displays high quantum yield (Φ = 0.86) and fluorescence enhancement following Cr3+ coordination within a wide pH range. DN2 contains a 8-hydroxyquinoline-carboxhydrazone tetradentate metal-binding moiety, forming a 1:1 complex with Cr3+. DN2 also exhibits significantly fluorescence enhancement but a much lower quantum yield following Cr3+ binding in aqueous solution. In contrast, their congener DN3, having a salicyl-carboxhydrazone tridentate binding site, does not exhibit any significant fluorescence variation following Cr3+ binding. These results demonstrate that the hydroxyl group is an important factor influencing the fluorescence response to Cr3+ in aqueous media.
TL;DR: Aryl coupled bifunctional guanidine, ArNC(H)C(NPri2)NC6H2Pri2-2,6-}2 (PrisoH)2, have been prepared by other routes as discussed by the authors.
Abstract: Reactions of alkali metal amides or phosphides with the bulky carbodiimide, ArNCNAr (Ar = C6H3Pri2-2,6), followed by aqueous work-ups, have yielded several guanidines, ArNC(NR2)N(H)Ar (R = cyclohexyl (GisoH) or Pri (PrisoH); NR2 = cis-NC5H8Me2-2,6 (PipisoH)), a bifunctional guanidine, {ArNCN(H)Ar}2{μ-N(C2H4)2N} (Pip(GisoH)2), and two phosphaguanidines, ArNC(PR2)N(H)Ar (R = cyclohexyl (CyP-GisoH) or Ph (PhP-GisoH)). A very bulky guanidine, ArNC{N(Ar)SiMe3}N(H)Ar (ArSi-Giso), and an aryl coupled bifunctional guanidine, {ArN(H)C(NPri2)NC6H2Pri2-2,6-}2 (PrisoH)2, have been prepared by other routes. All compounds have been crystallographically characterised and shown to exist in a number of isomeric forms in the solid state. These appear to be largely retained in solution. The deprotonation of GisoH with BunLi in either hexane or THF led to crystallographically characterised dimeric and monomeric complexes respectively, viz. [Li{Li(κ2-N,N′-Giso)2}] and [Li(THF)(η1-N,η3-Ar-Giso)]. Deprotonation of PrisoH and Pip(GisoH)2 with K[N(SiMe3)2] gave the unsolvated polymer, [{K(η1-N,η6-Ar-Priso)}∞], and the solvated complex, [{K(THF)2}{Pip(Giso)2}{K(THF)3}], respectively.
TL;DR: In this article, the main solvent factors that aid partitioning into the ketones are polarizability/dipolarity, hydrogen-bond basicity and hydrophobicity of the ketone.
Abstract: Literature data on partitioning of compounds from the gas phase to ketones and from water to ketones has been collected and analyzed through the Abraham solvation equations. It is shown that for partition into both dry and wet ketones the main solvent factors that aid partitioning into the ketones are the polarizability/dipolarity, hydrogen-bond basicity and hydrophobicity (size) of the ketones. Reliable equations have been established for partitioning from the gas phase and from water to dry acetone, dry butanone, dry cyclohexanone and to wet methyl isobutyl ketone. It is further shown that partitioning into dry butanone and dry cyclohexanone leads to different equations than partitioning into the wet solvents, and that data on partitioning into the wet and dry ketones cannot be combined.
TL;DR: A series of ligands LPh, Lnaph and Lanth which contain two bidentate pyrazolyl-pyridine termini separated by an aromatic spacer have been used to prepare tetrahedral cage complexes of the form [M4L6]Xn, in which a bis-bidentate bridging ligand spans each of the six edges of the M4 tetrahedron and one anion is bound in the central cavity as mentioned in this paper.
Abstract: A series of ligands LPh, Lnaph and Lanth, which contain two bidentate pyrazolyl–pyridine termini separated by an aromatic (1,2-phenyl, 2,3-naphthyl or 2,3-anthracenyl, respectively) spacer have been used to prepare tetrahedral cage complexes of the form [M4L6]Xn, in which a bis-bidentate bridging ligand spans each of the six edges of the M4 tetrahedron and one anion is bound in the central cavity. Several new examples have been structurally characterised, including an example with a new ligand (Lanth), the first example with a second-row transition metal ion [Cd(II)], and the first example of a cage containing a dianionic guest (hexafluorosilicate). The series of structurally similar Co(II) complexes [Co4L6(BF4)](BF4)7 (L = LPh, Lnaph and Lanth) have been examined in detail by NMR spectroscopy. The 1H NMR spectra are highly shifted between −110 and +90 ppm, but the spectra can be completely assigned by correlation of measured T1 relaxation times with distances of the protons in the complexes from the paramagnetic Co(II) centres. 1H DOSY measurements have been used to estimate diffusion constants which confirm the structural integrity of the cages in solution, and 19F DOSY measurements on the anions show that (i) the trapped [BF4]− anion diffuses at the same rate as the cage superstructure surrounding it, indicating that it is trapped inside the cage cavity; and (ii) the ‘free’ [BF4]− anions have diffusion rates consistent with substantial retardation due to ion-pairing with the 7+ complex cation.
TL;DR: A survey on the synthesis of CPNs and their related magnetic properties is given in this paper, where the authors show that the size of the nanoparticles, the magnetostatic interparticles and/or the NP-matrix interactions provide significant modification of the superparamagnetic relaxation regime.
Abstract: A survey on the synthesis of cyano-bridged coordination polymer nanoparticles (CPNs) performed in our group and on the study of their related magnetic properties is given. Two synthetic approaches consisting in the one-pot synthesis of soluble CPNs and in the sequential growth of CPNs onto appropriate matrices are reviewed. A special emphasis is placed on the magnetic properties of CPNs and the determination of the magnetic regime in these systems, which strongly depends on various factors. We show that the size of the nanoparticles, the magnetostatic interparticles and/or the NP–matrix interactions provide significant modification of the superparamagnetic relaxation regime.
TL;DR: In this paper, the photophysical properties of five BODIPY derivatives containing chalcogen atoms are compared to those of a chlorine atom containing BOWIPY, acting as a reference.
Abstract: Synthetic details and stationary and time-resolved photophysical properties of five BODIPY derivatives containing chalcogen atoms are presented. The photophysical data are compared to those of a chlorine atom containing BODIPY, acting as a reference. A strong impact in the HOMO–LUMO transition energy is achieved via nucleophilic substitution with chalcogen based units. Going from oxygen to tellurium a bathochromic shift in both absorption and emission spectra from the green to the near infrared region was observed. By employing fluorescence single photon timing experiments in two solvents of different polarity, the excited state dynamics and their solvent dependence indicate the presence of a mechanism involving a photoinduced charge transfer that dramatically affects the optical radiative processes of these derivatives.
TL;DR: The temperature dependence of the magnetic susceptibility, optical reflectivity and electrical conductivity of [Fe(HB(pz)3)2] (pz = pyrazolyl) revealed irreversible changes in the material during the low-spin to high-spin transition when the “as-prepared” sample was heated above ∼400 K for the first time as discussed by the authors.
Abstract: The temperature dependence of the magnetic susceptibility, optical reflectivity and electrical conductivity of [Fe(HB(pz)3)2] (pz = pyrazolyl) revealed irreversible changes in the material during the low-spin to high-spin transition when the “as-prepared” sample was heated above ∼400 K for the first time. During this first heating sequence, the initially fine powder sample became coarse, and its crystal structure changed from tetragonal to monoclinic. Single-crystals of the monoclinic form suitable for X-ray analysis could be isolated after the first thermal cycle, and their structure was resolved in the P21/n (Z = 4) space group. Successive cooling and heating cycles did not lead to further modification of the crystal structure, and the temperature dependence of the physical properties remained invariable. Remarkably, the electrical conductivity of the sample measured at 293 K dropped from 6.1 × 10−8 to 2.1 × 10−11 S m−1 following the first thermal cycle—suggesting possible applications of this material in read-only memory devices (ROM).
TL;DR: N-methylformamide is shown to be the best (and excellent) model for eye irritation and nasal pungency in humans, suggesting that the receptor site in these processes is protein-like.
Abstract: Literature data on partitioning of compounds from the gas phase to a number of amides and from water to the amides has been collected and analyzed through the Abraham solvation equations. The resulting equations are statistically good enough to be used for the prediction of further partition coefficients, and allow deductions to be made about the chemical properties of the amides, as solvents. For example, tertiary amides have no hydrogen bond property at all, secondary amides are rather weak hydrogen bond acids, and primary amides are stronger hydrogen bond acids than are alcohols as solvents. Equations for partitioning from the gas phase to amide solvents can also be used to test if the amides are possible models for a number of biological phases and biological processes. It is shown that no organic solvent is a suitable model for phases such as blood, brain, muscle, liver, heart or kidney, but that a number of rather non-polar solvents are models for fat. N-Methylformamide is shown to be the best (and excellent) model for eye irritation and nasal pungency in humans, suggesting that the receptor site in these processes is protein-like.
TL;DR: Chromogenic cyanide recognition in water was achieved by the use of a hydrophobic dye in micellar containers with high affinity for cyanide by the H2O/O2 mixture.
Abstract: Chromogenic cyanide recognition in water was achieved by the use of a hydrophobic dye in micellar containers.
TL;DR: In this paper, the basicities of a large number of organic bases and superbases, including nitrogen basic centers in various chemical environments occurring in phosphazenes, amidines, amines, anilines and pyridines, have been studied in acetonitrile by the isodensity polarized continuum model employing two DFT computational schemes differing in the basis sets for final single point calculations.
Abstract: The basicities of a large number of organic bases and superbases, including nitrogen basic centers in various chemical environments occurring in phosphazenes, amidines, amines, anilines and pyridines, have been studied in acetonitrile by the isodensity polarized continuum model employing two DFT computational schemes differing in the basis sets for final single-point calculations It turned out that the B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) method serves the purpose giving good agreement for basicities with experiment for both gas phase and acetonitrile solutions treating widely different bonding situations of basic nitrogen atoms on an equal footing An attempt is made to correlate the experimental pKa(MeCN) values with the proton affinities (PA) in MeCN The results are less accurate than those achieved by using basicities in acetonitrile In particular, the PA(MeCN)s frequently failed in reproducing the pKa(MeCN) values in systems possessing multiple intramolecular hydrogen (IMH) bonds formed via corona effects In such cases the use of basicities is mandatory instead A useful corollary of these calculations on systems with multiple IMH bonds is that comparison of the theoretical and experimental pKa values can provide an insight into the structure of the most stable conformations in solutions
TL;DR: In this article, the second-order nonlinear optical response in the dihydroazulene (DHA)-vinylheptafulvene (VHF) equilibrium has been investigated as a function of the nature of the substituent (R) on the phenyl ring by means of quantum chemistry calculations including electron correlation, frequency dispersion, and solvent effects.
Abstract: The contrast of second-order nonlinear optical response in the dihydroazulene (DHA)-vinylheptafulvene (VHF) equilibrium has been investigated as a function of the nature of the substituent (R) on the phenyl ring by means of quantum chemistry calculations including electron correlation, frequency dispersion, and solvent effects. By considering the hyper-Rayleigh scattering (HRS) response, the contrast for R = H and R = CH3 between the DHA and VHF forms is larger than 5 while the contrast between the cis and transVHF forms is close to 1. Adding the NH2 donor group in para position of the phenyl leads to a substantial increase of the HRS first hyperpolarizability of the three forms, which is detrimental to the contrast. Then, in the case of the NO2 acceptor group, a contrast is recovered because the HRS first hyperpolarizability of the DHA form is about 2–3 times larger than for both VHF forms. These variations of first hyperpolarizability as a function of the substituents as well as the associated contrasts have been explained in terms of donor/acceptor strengths and geometrical parameters.
TL;DR: In this paper, it was shown that dendritic phosphole oxides display intense emission in the aggregate and solid states, but no emission in solution, because the intramolecular rotational motions of the peripheral Dendritic groups linked to the phosphole oxide core are restricted.
Abstract: Dendritic phosphole oxides display intense emission in the aggregate and solid states, but no emission in solution, because the intramolecular rotational motions of the peripheral dendritic groups linked to the phosphole oxide core are restricted. This unique spectroscopic feature is ascribed to an aggregation-induced emission.
TL;DR: In this paper, the authors studied catalysts for the asymmetric Henry reaction involving copper(II) complexes of the chiral Schiff bases N,N,N′-(1R,2R)-(−)-1,2-cyclohexylenebis(3-hydroxysalicylideneamine) (H21) and H23, which is the reduced analogue of H21, and showed that both yield and enantioselectivity are enhanced when a second equivalent of Cu(OAc)2 is added to the catalyst.
Abstract: Catalysts for the asymmetric Henry reaction involving copper(II) complexes of the chiral Schiff bases N,N′-(1R,2R)-(−)-1,2-cyclohexylenebis(3-hydroxysalicylideneamine) (H21) and N,N′-(1R,2R)-(−)-1,2-cyclohexylenebis(3-ethoxysalicylideneamine) (H22), and H23, which is the reduced analogue of H21, have been studied. Whereas [Cu(1)] and [Cu(2)] give poor yields and enantioselectivity, [Cu(3)] produced moderate to high yields and enantioselectivities were optimal when reactions were carried out in toluene rather than a polar solvent. A significant finding is that both yield and enantioselectivity are enhanced when a second equivalent of Cu(OAc)2 is added to the catalyst. The single-crystal structures of [Cu(3)] and [Cu(1)(H2O)] are presented, and the host–guest interactions and molecular packing in the latter are compared with those in [Cu(2)(H2O)].
TL;DR: Four series of phosphorus dendrimers having various types of amine terminal groups (pyrrolidine, morpholine, methyl piperazine, or phenyl p Piperazine) are synthesized and used as transfection agents to deliver single- and double-stranded DNA into the three cell strains.
Abstract: Four series of phosphorus dendrimers (generations 1 and 4) having various types of amine terminal groups (pyrrolidine, morpholine, methyl piperazine, or phenyl piperazine) are synthesized. After protonation, the fourth generations of three of them are found water-soluble, and used for several biological experiments. First, the cytotoxicity of these polycationic dendrimers towards three cell strains (one healthy: HUVEC, and two cancerous: HEK 293 and HeLa) is assayed and found low. Second, their ability to interact with DNA is tested by electrophoresis: the dendrimer terminated by pyrrolidinium groups is found efficient to form dendriplexes. Finally, the polycationic dendrimers are used as transfection agents to deliver single- and double-stranded DNA into the three above-mentioned cell strains. Here also the dendrimer having pyrrolidinium groups is found the most efficient.