Solvatochromism in Mixtures of Hydrogen Bond Acceptor (HBA) Solvents with Water.

The UV/Vis absorption energies ν of Reichardt's dye B30 with respect to E(30) and 4-nitroaniline (NA) are investigated as a function of the solvent composition N in co-solvent/water mixtures. N. is the average molar concentration of the solvent mixture at a given solvent fraction z.

Understanding Refractive Index Changes in Homologous Series of Unbranched Organic Compounds Based on Beer's Law.

Changes of the refractive index for homologous series of hydrocarbons are usually plotted versus the density. While there is a clear linear dependence for alkanes and alkenes, the linearity deteriorates for homologous series with functional groups involving heteroatoms. The slope can even become negative, e.

Cold Atmospheric Plasma Exerts Antimicrobial Effects in a 3D Skin Model of Cutaneous Candidiasis.

Cutaneous candidiasis is characterized by an overgrowth of leading to skin inflammation and infection. Similar to bacteria, can develop tolerance to common antifungal drugs. Cold atmospheric plasma (CAP), with its proven antimicrobial properties, offers a promising alternative to the prevailing methods.

Empirical Hydrogen Bonding Donor (HBD) Parameters of Organic Solvents Using Solvatochromic Probes - A Critical Evaluation.

The solvatochromicity of established solvatochromic UV/Vis probes, which appear to be sensitive to the so-called hydrogen bond donor (HBD) property of the solvent, is analysed using the hydroxyl group density of alcoholic solvents D as a physical parameter in comparison to the pKa, the chemical benchmark for acidity. Reichardt's dye B30, Kosowers Z-indicator 1-ethyl-4-(methoxycarbonyl) pyridinium iodide (K), Kamlet-Tafts α, Dragos S parameter, Catalans SA scale, the cis-dicyano-bis (1,10-phenanthroline) iron II complex (Schilt's Ferrocyphen dye, Fe) and Gutmann's acceptor number (AN) have been investigated. The observed dependencies of the empirical polarity parameters as a function of D for several alcoholic solvent families requires a ompletely new physicochemical understanding of these established HBD parameters.

The Global Polarity of Alcoholic Solvents and Water - Importance of the Collectively Acting Factors Density, Refractive Index and Hydrogen Bonding Forces.

The D quantity represents the hydroxyl group density of alcoholic solvents or water. D is purely physically defined by the product of molar concentration of the solvent (N) and the factor Σn=n×f which reflects the number n and position (f-factor) of the alcoholic OH groups per molecule. Whether the hydroxyl group is either primary, secondary or tertiary is taken into account by f.

The Negative Solvatochromism of Reichardt's Dye B30 - A Complementary Study.

The UV/Vis spectra of a hypothetical negative solvatochromic dye in a solvent are theoretically calculated assuming the classical damped harmonic oscillator model and the Lorentz-Lorenz relation. For the simulations, the oscillator strength of the solvent was varied, while for the solute all oscillator parameters were kept constant. As a result, a simple change of the oscillator strength of the solute can explain the redshift and intensity increase of the UV/Vis band of the solute.

The influence of the cation structure on the basicity-related polarity of ionic liquids.

UV/Vis absorption data of ()-4-(2-[5-{4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-yl}thiene-2-yl]vinyl)-2-(dicyano-methylene)-3-cyano-5,5-dimethyl-2,5-dihydrofuran (ThTCF) as a solvatochromic probe is applied to examine the anion coordination strength ( of N(CN), BF, PF, N(Tf), CFCOO) as a function of the cation structure of ionic liquids. Several 1--alky-3-methylimidazolium- and tetraalkylammonium CH-NR-based ILs with different -alkyl chain lengths (R = -CH, -CH, -CH, -CH) are considered. UV/Vis absorption data of ThTCF show subtle correlations with hydrogen bond accepting (HBA) ability-related measurands such as Kamlet-Taft , Freire's , and Laurence parameter as a function of anion and cation structure.

Reversible and Stable Hemiaminal Hydrogels from Polyvinylamine and Highly Reactive and Selective Bis(-acylpiperidone)s.

Water-soluble bis(-acylpiperidone)s with aldehyde-like reactivity are reported to react rapidly with polyvinylamine at room temperature, providing unprecedented clean reaction products. Unlike most amine/ketone reactions that result in arbitrary mixtures of imines, aminals, hemiaminals, or hydrates, in the present study hemiaminals, aminals, or hemiaminal/aminal mixtures are exclusively found. Detailed NMR spectroscopy of solutions, gels, and solids, aided by model reactions, reveals that the hemiaminal/aminal ratio depends on pH, water content, and cross-linking density.

The physical significance of the Kamlet-Taft * parameter of ionic liquids.

The Kamlet-Taft dipolarity/polarizability parameters π* for various ionic liquids were determined using 4-tert-butyl-2-((dicyanomethylene)-5-[4-N,N-diethylamino)-benzylidene]-Δ3-thiazoline and 5-(N,N-dimethylamino)-5'-nitro-2,2'-bithiophene as solvatochromic probes. In contrast to the established π*-probe N,N-diethylnitroaniline, the chromophores presented here show excellent agreement with polarity measurement using the chemical shift of 129Xe. They do not suffer from additional bathochromic UV/vis shifts caused by hydrogen-bonding resulting in too high π*-values for some ionic liquids.

Complementary interpretation of E(30) polarity parameters of ionic liquids.

Reichardt's empirical ET(30) polarity parameter has been established as appropriate polarity scale for ionic liquids. In this study, the relationships of ET(30) of ionic liquids with the empirical Kamlet-Taft polarity parameters α (hydrogen bond donating ability), β (hydrogen bond accepting ability) and π* (dipolarity/polarizability) as well as Catalán's parameter set SA (solvent acidity), SB (solvent basicity), SP (solvent polarizability) and SdP (solvent dipolarity) are examined by means of multiple square correlation analyses. Several subtasks were carried out to address this main concern.

Ferrocenyl-Pyrenes, Ferrocenyl-9,10-Phenanthrenediones, and Ferrocenyl-9,10-Dimethoxyphenanthrenes: Charge-Transfer Studies and SWCNT Functionalization.

The synthesis of 1-Fc- (3), 1-Br-6-Fc- (5 a), 2-Br-7-Fc- (7 a), 1,6-Fc - (5 b), 2,7-Fc -pyrene (7 b), 3,6-Fc -9,10-phenanthrenedione (10), and 3,6-Fc -9,10-dimethoxyphenanthrene (12; Fc=Fe(η -C H )(η -C H )) is discussed. Of these compounds, 10 and 12 form 1D or 2D coordination polymers in the solid state. (Spectro)Electrochemical studies confirmed reversible Fc/Fc redox events between -130 and 160 mV.

Antibacterial Silicon Oxide Thin Films Doped with Zinc and Copper Grown by Atmospheric Pressure Plasma Chemical Vapor Deposition.

Zn-doped and Cu-doped SiO films were synthesized by atmospheric pressure plasma chemical vapor deposition to study their antibacterial efficiency against Gram-negative Escherichia coli and their cytotoxic effect on the growth of mouse cells. Zn-rich and Cu-rich particles with diameters up to several microns were found to be homogeneously distributed within the SiO films. For both doping elements, bacteria are killed within the first three hours after exposure to the film surface.

Design of nanostructured hybrid materials: twin polymerization of urethane-based twin prepolymers.

Organic-inorganic hybrid materials with urethane functionalities were obtained by simultaneous twin polymerization of twin prepolymers in combination with the ideal twin monomer 2,2'-spirobi[4-1,3,2-benzodioxasiline]. The twin prepolymers consist of a urethane-based prepolymer with reactive terminal groups which can react during the twin polymerization process. Nanostructured hybrid materials with integrated dialkylsiloxane crosslinked urethane structures, phenolic resin and SiO are obtained in a one pot process.

Ternary composites by an hydrolytic polymerization process.

Polyamide 6/modified silica composite materials have been prepared by a coupled polymerization procedure. For this purpose, the three-component-system we presented in a previous publication, consisting of ε-aminocaproic acid (ε-ACA), ε-caprolactam (ε-CL), and 1,1',1'',1'''-silanetetrayltetrakis-(azepan-2-one) (Si(ε-CL)), has been combined with other silicon monomers with one or two methyl groups (MeSi(ε-CL) and MeSi(ε-CL)). The simultaneous polymerization of ε-CL and silicon monomers leads to the formation of silica/polysiloxane particles and the surrounding polyamide 6 matrix in one step.

Electronic Structure Calculations and Experimental Studies on the Thermal Initiation of the Twin Polymerization Process.

Presented here is a combined computational and experimental study on the thermal initiation process of the twin polymerization. Although thermally initiated twin polymerization offers a versatile scheme for obtaining hybrid organic/inorganic nanocomposite materials, the mechanism for its initiation is very different from the proton-initiated twin polymerization. In this study, the basic mechanism of the early steps of the polymerization process of 4 H,4 H'-2,2'-spirobi[benzo[d][1,3,2]dioxasiline] was investigated by using electronic structure calculations in conjunction with experimental differential scanning calorimetry studies.

Kinetics of Electrophilic Alkylations of Barbiturate and Thiobarbiturate Anions.

Second-order rate constants (k) of the reactions of various barbiturate anions such as the parent barbiturate, 1,3-dimethylbarbiturate, 2-thiobarbiturate, and 1,3-diethyl-2-thiobarbiturate with diarylcarbenium ions and Michael acceptors have been determined in dimethyl sulfoxide solution at 20 °C. The reactivity parameters N and s of the barbiturate anions were derived from the linear plots of log k versus the electrophilicity parameters E of these reference electrophiles, according to the linear-free-energy relationship log k (20 °C) = s (E + N). Several reactions of these nucleophiles with benzylidenemalononitriles and quinone methides proceeded with reversible formation of the new C-C-bond followed by rate-determining proton shift.

Interactions of Enolizable Barbiturate Dyes.

The specific barbituric acid dyes 1-n-butyl-5-(2,4-dinitro-phenyl) barbituric acid and 1-n-butyl-5-{4-[(1,3-dioxo-1H-inden-(3 H)-ylidene)methyl]phenyl}barbituric acid were used to study complex formation with nucleobase derivatives and related model compounds. The enol form of both compounds shows a strong bathochromic shift of the UV/Vis absorption band compared to the rarely coloured keto form. The keto-enol equilibria of the five studied dyes are strongly dependent on the properties of the environment as shown by solvatochromic studies in ionic liquids and a set of organic solvents.

Electronically Strongly Coupled Divinylheterocyclic-Bridged Diruthenium Complexes.

Complexes [{Ru(CO)Cl(PiPr3 )2 }2 (μ-2,5-(CH-CH)2 -(c) C4 H2 E] (E=NR; R=C6 H4 -4-NMe2 (10 a), C6 H4 -4-OMe (10 b), C6 H4 -4-Me (10 c), C6 H5 (10 d), C6 H4 -4-CO2 Et (10 e), C6 H4 -4-NO2 (10 f), C6 H3 -3,5-(CF3 )2 (10 g), CH3 (11); E=O (12), S (13)) are discussed. The solid state structures of four alkynes and two complexes are reported. (Spectro)electrochemical studies show a moderate influence of the nature of the heteroatom and the electron-donating or -withdrawing substituents R in 10 a-g on the electrochemical and spectroscopic properties.

Highly Lewis Acidic Arylboronate Esters Capable of Colorimetric Turn-On Response.

A series of boronate-π-acceptor compounds containing different types of π bridges (1,4-phenylen or thien-2,5-diyl or furan-2,5-diyl) that link the switchable boronate ester group with the efficient TCF acceptor group (TCF=2-dicyanomethylen-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran) has been synthesized. A TCF chromophore of this type undergoes transition to a donor-π-acceptor compound upon coordination of Lewis bases at the Lewis acidic boron center, which is accompanied by an enhanced intramolecular charge-transfer interaction. The Lewis acid character has been investigated by spectroscopic measurements (UV/Vis, NMR spectroscopies) as well as DFT and ab initio-based calculations.

Twin Polymerization--a New Principle for Hybrid Material Synthesis.

Twin polymerization is a novel modular approach for the synthesis of hybrid materials. Using this strategy two distinct polymers of either inorganic or organic nature are produced from a single source monomer in a mechanistically coupled process. Twin polymerization is an elegant way for producing nanostructured organic-inorganic hybrid materials of composition and morphology on demand.

Zirconium and Hafnium Twin Monomers for Mixed Oxides.

The synthesis of Zr and Hf twin monomers of type [M(2-OCH C H O) (x HOCH C H O)] (3, M=Zr, x=0; 4, M=Hf, x=1) and M[(2-OCH -C H O) (2-HOCH -C H OH)] (5, M=Zr; 6, M=Hf) by reacting M(OR) (M=Zr, R= C H , 1; M=Hf, R= C H , 2) with 2-furylmethanol or 2-hydroxybenzyl alcohol is discussed. Complexes 3-6 were homopolymerized under acidic conditions. Additionally, 5 and 6 were copolymerized with 2,2'-spirobi[4 H-1,3,2-benzodioxasiline] (SBS).

Atmospheric pressure plasma CVD as a tool to functionalise wound dressings.

The main goal of this investigation was the preparation of an antibacterial layer system for additional modification of wound dressings with atmospheric plasma. Furthermore, the modified wound dressings were checked on there bactericidal and cytotoxic activity. The layer system was applied by using a novel atmospheric pressure plasma chemical vapour deposition technique on a variety of textile substrates which are suitable as wound dressing materials.

A non-aqueous procedure to synthesize amino group bearing nanostructured organic-inorganic hybrid materials.

Amino-functionalized organic-inorganic hybrid materials with a narrow distributed nanostructure of 2-4 nm in size were obtained by means of a template-free and non-aqueous procedure. Simultaneous twin polymerization of novel amino group containing twin monomers with 2,2'-spirobi[4H-1,3,2-benzodioxasiline] has been applied for this purpose. The amino groups of the organic-inorganic hybrid material are useful for post derivatization.

Thermally induced twin polymerization of 4H-1,3,2-benzodioxasilines.

The twin monomer 2,2'-spirobi[4H-1,3,2-benzodioxasiline] (1) can be polymerized to nanostructured SiO2/phenolic-resin composite material by thermally induced twin polymerization. Thermally induced twin polymerization represents a way to produce nanocomposites simply by thermal induction of twin monomers. Besides 1, the thermal reaction of several related salicylic (2-oxybenzylic) silicon molecules has been investigated.

Dipolarity versus polarizability and acidity versus basicity of ionic liquids as a function of their molecular structures.

The four empirical solvent polarity parameters according to the Catalán scale--solvent acidity (SA), solvent basicity (SB), solvent polarizability (SP), and solvent dipolarity (SdP)--of 64 ionic liquids (ILs) were determined by the solvatochromic method. The SA parameter was determined solely by using [Fe(II)(1,10-phenanthroline)2(CN)2] (Fe), the SB parameter by using the pair of structurally comparable dyes 3-(4-amino-3-methylphenyl)-7-phenylbenzo[1,2-b:4,5-b']difuran-2,6-dione (ABF) and 3-(4-N,N-dimethylaminophenyl)-7-phenylbenzo[1,2-b:4,5-b']-difuran-2,6-dione (DMe-ABF), and the SP and SdP parameters by using the homomorphic pair of 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benzylidene]-Δ(3)-thiazoline (Th) and 2-[4-(N,N-dimethylamino)benzylidene]malononitrile (BMN). The separation of SP and SdP for a set of 64 various ILs was performed for the first time.