Syntheses and properties of water-soluble Nile Red derivatives

Nile Red (compound A) fluoresces at about 530 nm with good quantum yields in apolar solvents. In more polar ones its fluorescence emission shows a dramatic, and potentially useful, shift to about 640 nm, but its quantum yield is significantly reduced. Further, Nile Red has a very poor solubility in aqueous media. The hypothesis tested in this paper is that Nile Red derivatives that incorporate water-solubilizing groups will tend to fluoresce with good quantum yields in aqueous media, and in the more useful wavelength range around 640 nm. Thus three Nile Red derivatives, 1-3, were prepared. Compound 1 had three hydroxyl groups more than Nile Red, but was surprisingly insoluble in aqueous media. However, the dicarboxylic acid 2 and carboxylic/sulfonic acid derivative 3 showed excellent water solubilities. Spectral data for 2 and 3 showed that they do indeed fluoresce with good quantum yields in the 640 nm region in aqueous media. These properties of compounds 2 and 3 might be useful in the development of fluorescent probes for biotechnology.     

Syntheses and spectral properties of 2-Thiobiotin and biotin derivatives

A series of methylated derivatives of 2-thiobiotin (2-4) have been prepared as potential aids in elucidation of the mechanism of biotin catalysis. The syntheses and mass, infrared, ¹H nmr, and ¹³C nmr spectral properties for these substrates, their 2-thiobiotin precursors (6, 10-14) and the corresponding biotin analogs (1, 15, 31-34) are described. A series of selective proton-proton and proton-carbon decoupling experiments were employed to secure a number of the ¹H and ¹³C nmr assignments. Consistent patterns noted throughout the data set proved helpful in structure determination.     

Syntheses of terminally functionalized polyisobutylene derivatives using diazonium salts

A new strategy for the synthesis of end‐functionalized polyisobutylene (PIB) oligomers is detailed. Commercially available vinyl‐terminated PIB oligomers were modified to form aniline‐terminated PIB via an aromatic electrophilic substitution reaction. The PIB‐bound aryl amines so formed were then converted into diazonium salts using isopentyl nitrite and an acid in methylene chloride. These salts served as versatile intermediates in synthetic reactions affording azo dye‐containing PIB derivatives and other terminally‐functionalized PIB derivatives not readily available by other reactions. The advantages and limitations of various name reactions including diazo couplings, Sandmeyer reactions, dediazoniations, and Heck reactions are discussed. The kinetics of polar substitution reactions at the termini of these nonpolar oligomers and the effects of solvent on these reactions were also examined. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and second-order nonlinear optical properties of push-pull BODIPY derivatives

A series of boron dipyrromethene derivatives bearing an electron-donating 4-(dimethylamino)phenylethynyl group and an electron-withdrawing 4-nitrophenylethynyl group in the opposite 2- and 6-positions have been synthesized by Knoevenagel condensation followed by sequential Sonogashira coupling reactions. The compounds have been fully characterized with various spectroscopic methods. Their electrochemical properties have also been studied by cyclic voltammetry in CH₂Cl₂. It has been found that expansion of the π systems by introduction of the 4-dodecyloxystyryl or 4-(dimethylamino)phenylethynyl group results in lowering of the first oxidation potential, while the first reduction potential remains relatively unaffected. The second-order nonlinear optical properties of these compounds have also been studied by electric-field-induced second-harmonic generation method in CHCl₃. The values of the dot product μ·β are in the range from 94×10^?48 to 330×10^?48 esu at 1907 nm, depending the substituents at the 3- and 5-positions.     

Syntheses and properties of functionalized oxacalix[4]arene porphyrins

Six new functionalized oxacalix[4]arene porphyrins have been synthesized via a high-yielding ‘3+1’ condensation between meso-(3,5-dihydroxyphenyl)triphenylporphyrin and readily available new fluorodinitrobenzene-containing trimers. The X-ray structure of one linear trimer is presented. The synthesis of a porphyrin containing two oxacalix[4]arene moieties is also reported using a similar strategy. ¹H NMR data and computer calculations using the AM1 semiempirical method incorporated into the Spartan program indicate that the oxacalix[4]arene porphyrins adopt 1,3-alternating conformations. The photophysical properties of the oxacalix[4]arene porphyrins were investigated.     

Synthesis and spectroscopic properties of highly water-soluble perylene derivatives

Most known perylene diimides are lipophilic, with few exceptions of hydrophilic derivatives. Even in the latter case, the compounds have limited water solubility and show a strong tendency to self-aggregation. In this paper we present the synthesis of four new perylene derivatives with three and four basic side chains, obtained by functionalizing the bay-area of perylene. These molecules show great solubility in aqueous media as hydrochlorides and their tendency to self-aggregate is remarkably reduced with respect to the previously synthesized two-chained perylene diimides. Their different spectroscopic properties in various solvents and conditions are reported and discussed.     

Nitrosyl rhenium complexes: Syntheses,properties, and structures of acetylacetonato derivatives

Some new complexes of rhenium containing monocoordinating acetylacetone viz. [Re(NO)(acac)₂(Cl)H₂O], Re(NO)(acac)₃(acacH)(H₂O)₂ have been synthesized by reacting acetylacetone with either Re(NO)Cl₃ · H₂O or Re(NO)(OH)₃ · H₂O. The preparation of [Re(NO)(py)(acac)₂(Cl) · H₂O], [Re(NO)(acac)(OH)(Cl) · H₂O], [Re₂(NO)₂(acacH)₃(acac)₂ · Cl₄], [Re(NO)(acac)₂(OH) · H₂O] · 2 H₂O have also been described. These complexes were characterized through their elemental analyses, u.v., vis, i.r., ¹Hn.m.r., magnetic, and conductance data.     

Syntheses and biological properties of new 8-fluorocarbapenem derivatives

8-Fluorocarbapenem derivatives having various C-3 side chains were synthesized to study for the structure-activity relationship of carbapenems by in vitro biological evaluation. The introduction of fluorine at C-8 of racemic PS-5 led to slight improvements of the antimicrobial activity and the stability to renal dehydropeptidase-I. When D-cysteine was additionally introduced to the C-3 position of (+/-)-8-fluorocarbapenem, the diastereomeric separation of the 8-fluorocarbapenems became feasible. As expected from penicillins and cephalosporins, (+)-8-fluoro-3-D-cysteinylcarbapenem (+)-7a was antimicrobially active, whereas (-)-7b was inactive. It is worth noting, however, that (+)-7a was significantly more sensitive to renal dehydropeptidase-I than (-)-7b. Irrespective of the presence of fluorine at C-8, basic S-side chains at C-3, such as the pyridyl and pyrrolidyl groups, significantly improved in antimicrobial activity and dehydropeptidase-I stability. The combination of 8-fluorination with C-3 basic side chains in 7c--g resulted in a marked improvement of antimicrobial activity and dehydropeptidase-I stability.     

Synthesis and properties of water-soluble derivatives of fullerene C60

Procedures for synthesized of water-soluble forms of fullerene C₆₀ and its derivatives were developed.     

DNA-binding properties and photocleavage activity of cationic water-soluble chlorophyll derivatives

Three cationic water-soluble chlorin e(6) derivatives, that is, 6a-,gammab-,7c-tris(2-trimethylammonioethyl)chlorin e(6) (1), 6a-,gammab-,7c-tris(3-methylpyridiniummethyl)chlorin e(6) (2), and 6a-,gammab-, 7c-tris(2-trimethylammonioethyl)-2-(3-trimethylammonioprop-1-enyl)chlorin e(6) (3), have been designed and synthesized to allow the study of their DNA-binding and -photocleavage activities. The DNA-unwinding assay, measurements of melting temperatures of double-stranded DNA, and the induced CD and visible absorption spectra have revealed that 1 and 3 are intercalated into the base pairs of the double-helical DNA, while 2 is bound to outside the minor groove of the double-helical DNA. The cationic water-soluble chlorin e(6) derivatives effectively cleave the double-helical DNA under photoirradiation and the DNA-photocleavage activity increases in the order 3>1>2. The DNA-binding and -photocleavage characteristics of the three cationic water-soluble chlorin e(6) derivatives are influenced by aspects of their molecular structure, such as the kind, number, and position of the cationic substituents.     

Syntheses of functionalized ferratricarbadecaboranyl complexes

The reactions of nitriles (RCN) with arachno-4,6-C(2)B(7)H(12)(-) provide a general route to functionalized tricarbadecaboranyl anions, 6-R-nido-5,6,9-C(3)B(7)H(9)(-), R = C(6)H(5) (2(-)), NC(CH(2))(4) (4(-)), (p-BrC(6)H(4))(Me(3)SiO)CH (6(-)), C(14)H(11) (8(-)), and H(3)BNMe(2)(CH(2))(2) (10(-)). Further reaction of these anions with (eta(5)-C(5)H(5))Fe(CO)(2)I yields the functionalized ferratricarbadecaboranyl complexes 1-(eta(5)-C(5)H(5))-2-C(6)H(5)-closo-1,2,3,4-FeC(3)B(7)H(9) (3), 1-(eta(5)-C(5)H(5))-2-NC(CH(2))(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (5), 1-(eta(5)-C(5)H(5))-2-[(p-BrC(6)H(4))(Me(3)SiO)CH]-closo-1,2,3,4-FeC(3)B(7)H(9) (7), 1-(eta(5)-C(5)H(5))-2-C(14)H(11)-closo-1,2,3,4-FeC(3)B(7)H(9) (9), and 1-(eta(5)-C(5)H(5))-2-H(3)BNMe(2)(CH(2))(2)-closo-1,2,3,4-FeC(3)B(7)H(9) (11). Reaction of 11 with DABCO (triethylenediamine) resulted in removal of the BH(3) group coordinated to the nitrogen of the side chain, giving 1-(eta(5)-C(5)H(5))-2-NMe(2)(CH(2))(2)-closo-1,2,3,4-FeC(3)B(7)H(9) (12). Crystallographic studies of complexes 3, 5, 7, 9, and 11 confirmed that these complexes are ferrocene analogues in which a formal Fe(2+) ion is sandwiched between the cyclopentadienyl and tricarbadecaboranyl monoanionic ligands. The metals are eta(6)-coordinated to the puckered six-membered face of the tricarbadecaboranyl cage, with the exopolyhedral substituents bonded to the low-coordinate carbon adjacent to the iron.     

Effect of substituents on spectral,luminescent, and time-resolved spectral properties of 2,6-diarylidene derivatives of cyclohexanone

Spectral, luminescent, and time-resolved properties of 2,6-dibenzylidene cyclohexanone and its symmetric derivatives in the para-position of benzene ring (dimethoxy, dimethylthio, and bis-N,N-diethylamino groups) have been studied in media of different polarity (cyclohexane, acetonitrile, dimethylsulfoxide, and methanol). Introduction of electro-donating substituents to dibenzylidene cyclohexanone results in the red shift of the absorption maximum by 81–138 nm upon passing from the nonpolar to polar medium. Bis(N,N-diethylamino)dibenzylidene cyclohexanone fluoresces in polar solvents, acetonitrile, dimethylsulfoxide and methanol. The bathofluoric shift on passing from acetonitrile to methanol is 39 nm. The relative quantum yield of fluorescence in acetonitrile is seven times that in methanol. An intermediate species absorbing in the range of 400–560 nm with a maximum at 430–460 nm has been observed under the action of the laser pulse on dibenzylidene cyclohexanone solutions in acetonitrile. The intermediate species has a lifetime of 40, 20, and 7 μs for dibenzylidene cyclohexanone and its dimethylthio and dimethoxy derivatives, respectively.     

Syntheses,crystal structures,and properties of nickel and cadmium complexes containing imidazole derivatives

[Ni₃(C₁₃H₉N₂O)₅(CH₃OH)₂] (1) and [Cd(C₁₂H₈N₃)₃] (2) were synthesized in methanol and characterized by elemental analyses, IR spectra, and X-ray diffraction. Complex 1 is trinuclear with three unsymmetric Ni(II)'s having different coordinated environments bridged by four oxygen atoms from five ligands. Intermolecular antiferromagnetic interactions were observed in 1. Complex 2 is mononuclear with Cd(II) six-coordinate by six nitrogen atoms from three bidentate HPBM anions. Complex 2 shows emission maxima in the blue region.     

Syntheses,structure, and electrochemical properties of unsymmetrical crown‐annelated TTF derivatives

A series of new crown‐ether annelated TTF derivatives 2a, 2b, 2c, 3 and 5 have been synthesized and characterized by melting points, NMR, IR and ESI‐MS. The crystal structure of compound 3 , 2, 3‐dithia‐(5′,8′‐dioxaoctyl)‐6,7‐ethylenedithiatetrathiafulvalene, has been determined by X‐ray crystallography. Redox properties of all these compounds have been investigated by cyclic voltammetry and each compound shows two reversible single‐electron redox couples. The results indicate that 3 is responsive for Li⁺, but not to other alkali metal cations, such as Na⁺ and K⁺. Although with the same cavity, compounds 2c and 5 show marked changes upon the addition of sodium perchlorate, while there is no significant response for 2a and 2b at the same condition.     

Synthesis of functionalized spiropyran and spirooxazine derivatives and their photochromic properties

Three series of functionalized spiropyrans and spirooxazines derivatives were synthesized and their photochromic properties were investigated in particular regard to the fatigue resistance, the lifetime of the colored merocyanine form and the interaction of the colored form molecule. (1) Spiropyrans 5 and spironaphthooxazines 6 having an antioxidant group as a pendant exhibited higher fatigue resistance than that of the parent spiro compounds in solution. In particular, spiropyrans 5 showed higher resistance than parent compound 1 in the presence of an equimolar amount of the corresponding antioxidant. (2) bis-Spironaphthooxazines 8a–8i and 10 connected through a phosphoryl group exhibited higher fatigue resistance and longer lifetime of the colored merocyanine form than those of the parent spirooxazine 7. (3) Symmetrical bis-spiro photochromic compounds 15 and 16 and unsymmetrical bis-spiro compounds 13, 14 and 17 were synthesized. The bis-spiro photochromic compounds were found to undergo intramolecular interaction between the colored merocyanine forms.     

Synthesis and spectral properties of 1,4-naphthoquinone sulfanyl derivatives

Reactions of 2,3-dichloro-1,4-naphthoquinone with hexadecanethiol and other alkanethiols in ethanol in the presence of sodium carbonate afforded new symmetric and unsymmetrical sulfanylnaphthoquinone dyes.     

pH-dependent spectral properties of para-aminobenzoic acid and its derivatives

The local environment dictates the structural and functional properties of many important chemical and biological systems. The impact of pH on the photophysical properties of a series of para-aminobenzoic acids is examined using a combination of experimental spectroscopy and quantum chemical calculations. Following photoexcitation, PABA derivatives may undergo an intramolecular charge transfer (ICT) resulting in the formation of a zwitterionic species. The thermodynamics of the excited state reaction and temperature-dependence of the radiative emission processes are evaluated through variable temperature fluorescence spectroscopy carried out in a range of aqueous buffers. Quantum chemical calculations are used to analyze structural changes with modifications at the amine position and different protonation states. The ICT is only observed in the tertiary amine, which calculations show has more sp(2) character than the primary or secondary amines. Thermodynamic analysis indicates the ICT reaction is driven by entropy.     

Preparation,spectral and thermal properties of new Isoflavone derivatives: mesomorphic properties and DFT studies

The four new homologous series of symmetric Isoflavon dimers were synthesised using varied alkyl/aryl diamines in linear sense. The chemical structures of the molecules were characterised by IR, NMR and CHNS analysis. Further, Liquid crystalline properties were verified using the combination of differential scanning calorimetry (DSC) and polarised optical microscope (POM). The molecular systems studied here reveal that LC property depends on the length of the middle connecting diamine spacer along with terminal alkyl spacer. The lower members favour to exhibit smectic A phase, whereas higher members exhibit nematic mesophase. The nature of LC property behaviours is supported by molecular geometries studied by DFT calculations.     

Synthesis,spectral, electrochemical properties,and photovoltaic performance of structurally constrained BODIPY dyes with 4,4-dimethyltriphenylamine at the 2,6-positions

Novel symmetrical D–A–D type of BODIPY derivatives (DTPA–BDP) were synthesized successfully. The introduction of chromophoric units makes the molecule absorption wavelengths spanning the ranges of 300–800 nm and shifts the emission to 793 nm in red and near-infrared region. Bulk heterojunction solar cells with DTPA–BDPs as electron donor and PC₆₁BM as electron acceptor exhibited photovoltaic properties with a power conversion efficiency of 0.77%, an open-circuit voltage of 0.70 V.