What is the basic chromophore of a dye?

Taking the 4,5-diphenyl-substituted 2-dimethylamino-3-azacyclopentadienone (4) as an example its colour has been discussed in relation to different basic chromophores (parent chromophores). The parent chromophore can be defined either as the structure which has nearly the same absorption wavelength as the dye under consideration or as the substructure which is electronically most closely related to the dye. In the case of4 both considerations lead to different results. Based on the correlation diagram between the electronic states involved in the electronic excitation the long-wavelength absorption of4 is better understood in terms of the merocyanine parent chromophore than in terms of a betainic substructure, which should have the same colour as4 and is the parent chromophore according toKlessinger. This conclusion is drawn fromPPP configuration analysis of the wavefunctions of4 relative to different molecular substructures. The molecular geometry predicted by the geometry-optimized MINDO/3 and QCFF/Pi calculations provided additional arguments in favour of the cyclomerocyanine structure of4. In respect to the colour4 belongs to a new series of cyclic-conjugated chromophoric systems.     

Tuning the solid-state emission of the analogous GFP chromophore by varying alkyl chains in the imidazolinone ring

New analogues of green fluorescent protein (GFP) chromophore mGFP-Cn (n = 1, 3, 5, 11) with alkyl chains of different lengths in the imidazolinone rings were synthesized and their crystal structures were determined. These GFP-like chromophores are all emissive in the solid state. And the solid-state emission quantum yields of increase by extending the lengths of alkyl chains, owing to the fact that the intermolecular pi-pi interactions are significantly weakened based on their crystal structures.     

Synthesis of some nitrogen heterocycles and in vitro evaluation of their antimicrobial and antitumor activity

Treatment of ethyl β-aryl-α-cyanoacrylate (2a, b) with thiourea, guanidine hydrochloride, and thiosemicarbazide in presence of anhydrous potassium carbonate in methanol led to formation of pyrimidine derivatives 3 and 5 and thiosemicarbazone derivative 9. Thiazole derivative 10 was prepared via cyclization of thiosemicarbazone derivative 9 with 4-methoxy phenacyl bromide. Acetylation of 3a, 5, and 10 with acetic anhydride yielded the acetoxy and N-acetyl derivatives 4, 6, and 11. The mass-spectral fragmentation patterns of nitrogen heterocycles were investigated to elucidate the structure of the prepared compounds. Biological studies of nitrogen heterocycles were carried out to investigate their antimicrobial and anticancer activities; it was found that compounds 5, 10, and 11 were highly active against bacteria and fungi, and compounds 3a and 3b were also active against bacteria and fungi.     

Cytotoxicity evaluation of coumarin derivatives containing 4-bromophenyl or anthracene moieties

The cytotoxic properties of four synthesized coumarin derivatives containing 4-bromophenyl or anthracene moieties against the human hepatocellular carcinoma cell lines (HepG-2) were investigated in vitro by use of the sulforhodamine B (SRB) assay. The four coumarin derivatives are 3-(4-bromophenyl)-benzo[5,6]coumarin (1a), 3-(4-bromophenyl)-7-(N,N-diethylamino)coumarin (1b), 3-(4-(anthracen-10-yl)phenyl)-benzo[5,6]coumarin (2a), and 3-(4-(anthracen-10-yl)phenyl)-7-(N,N-diethylamino)coumarin (2b). The preliminary results indicate that 1a, 2a, and 2b have significant cytotoxicity against HepG-2 whereas 1b has a growth-promotion effect.     

Synthesis of aryl-substituted or aryl-fused N-hydroxyethyl and N-hydroxymethypyrazole derivatives as potential ligands for the estrogen receptor

A new series of N-hydroxyethylpyrazole (12a–f) and N-hydroxymethylpyrazole derivatives (15a–f) were designed for their estrogenic activities, having a 11.0 ± 0.5 Å distance between their two hydroxyl groups, aliphatic–OH and phenolic–OH similar to 17β-estradiol (E2) as an endogenous hormone. To synthesize the title compounds, the key intermediate 1,3-dicarbonyl derivatives (2 and 8), were treated with hydrazine hydrate to produce the pyrazole ring 5 and 9. Further hydroxyalkylation of the latter produced the title pyrazoles. The position of hydroxyethyl or hydroxymethyl substituents in the products was determined through 2D NOE NMR spectroscopy.     

One-pot microwave-assisted solvent-free synthesis,theoretical and experimental studies on barrier rotation of C–N bond of N-alkenyl-1,2,3-triazoles

The reactions on benzotriazoles continue to happen to reach interesting varieties of their derivatives. This study reports a fast one-pot microwave-assisted solvent-free synthesis of N-alkenyl-1,2,3-benzotriazole (3, 5, and 7) and 1-(2-Alkyloxycarbonyl-vinyl)-1H-[1–3] triazole-4-carboxylic acid methyl ester (8 and 9) derivatives by nucleophilic addition reactions of 1,2,3-benzotriazole (C₆H₅N₃) (1) and 1H-[1–3] triazole-4-carboxylic acid methyl ester (C₄H₄N₃O₂) (1′) with R-propiolates (R = Me, Et; 2 & 4) and phenylacetylene 6 in good yields. The values of activation energy for rotation around C–N bond in the synthesized N-alkenyl-1,2,3-triazole compounds were studied by DFT-B3LYP/6-31G* method.     

Synthesis and characterization of new thienylpyrrolyl-benzothiazoles as efficient and thermally stable nonlinear optical chromophores

The synthesis and full characterization of new chromophores with second-order nonlinearities containing thienylpyrrolyl and benzothiazolyl moieties are reported. The solvatochromic behavior of the compounds was investigated. The hyperpolarizabilities β of derivatives 4-6 were measured using hyper-Rayleigh scattering and thermogravimetric analysis (TGA) was used to evaluate their thermal stability. The experimental results indicate that strong nonlinearity is balanced by good thermal stability especially for chromophores 6b and 6c, making them good candidates for NLO applications.     

Crystalline inclusion compounds derived from bulky organosilicon hosts – design, synthesis, structure and stability

New organosilicon compounds 1–3 featuring bulky triphenylsilyl moieties attached to rigid linear or trigonal spacer units have been synthesized and demonstrated to act as clathrate hosts, yielding crystalline inclusion compounds mostly with apolar and aprotic dipolar guest molecules, while the nonbulky dimethylphenylsilyl or trimethylsilyl substituted analogous compounds 4 and 5, which were also synthesized, proved inefficient. X-ray crystal structures of the inclusion compounds 1·DMF (1:1), 1·pyridine (1:1), 2·1,4-dioxane (2:1), 2·pyridine (2:1), 2·p-xylene (2:1), 2·H₂O (2:1) as well as of the unsolvated compounds 2 and 5 are described, and thermal stability studies of selected clathrates are reported.     

Synthesis of some new α,α-dioxoketene-N,S- and -N,N-acetals derived from secondary aliphatic amines

A total of 11 new α,α-dioxoketene- N,S -acetals (2a–2k) and two new α,α-dioxoketene- N,N -acetals (3j and 3k) have been synthesised by treating 3-[bis(methylthiol)methylene]pentane-2,4-dione (1) with increasing mole ratios of secondary aliphatic amines at room temperature, in either toluene or ethanol. Eight non-cyclic N -methylalkyl and N -ethylalkyl amines and the azacyclopentane of pyrrolidine yielded exclusively mono-substituted N,S -acetals (2a–2i), while the azacyclohexanes of piperidine and morpholine yielded the mono-substituted N,S -acetals 2j and 2k and the double-substituted N,N -acetals 3j and 3k. The conversion yields for the reactions in ethanol are considerably higher than those in toluene. Furthermore, the secondary aliphatic amines with an N -methylalkyl moiety, which have one primary α-carbon and less steric crowding around the nucleophilic nitrogen, appear to be more reactive towards 1 than those with the N -ethylalkyl group, which have two primary α-carbons; further, the latter amines are more reactive than the amines with secondary α-carbons.     

Synthesis and evaluation of some quinoline Schiff bases as a corrosion inhibitor for mild steel in 1 N HCl

N-((2-chloroquinolin-3-yl)methylene)aniline (CQM) and N-((2-chloroquinolin-3-yl)methylene)-5-methylthiazol-2-amine (CQMA) were synthesized. The effect of CQM and CQMA have been investigated against mild steel (MS) in 1 N HCl solutions using conventional weight loss, potentiodynamic polarization, linear polarization, electrochemical impedance spectroscopy, UV–Vis spectroscopy and scanning electron microscopic studies. The losses in the weights of MS samples have proved that both CQM and CQMA are efficient inhibitors. The mixed mode of inhibition was confirmed by electrochemical polarizations. The adsorptions of these inhibitors are found to follow the Langmuir adsorption isotherm. CQM and CQMA adsorbs on the MS sample by chemisorptions.     

Tribromogermyl monochelates — derivatives of N,N-disubstituted 2-hydroxycarboxylic amides

Reactions of GeBr₄ with N,N-dimethyl-2-trimethylsiloxypropionamide (2a), (S)-2-trime-thylsiloxypropionpyrrolidide ((S)-2b), and N,N-dimethyl-O-(trimethylsilyl)mandelamide (2c) afforded pentacoordinated neutral (O,O)-monochelates, viz., N,N-dimethyl-2-tribromoger-myloxypropionamide (3a), (S)-2-tribromogermyloxypropionpyrrolidide ((S)-3b), and N,N-dimethyl-O-(tribromogermyl)mandelamide (3c), respectively. X-ray diffraction study was performed for tribromides 3a, (S)-3b, and 3c, as well as for the N,N-dimethylmandelamide (1c) described earlier. According to the X-ray diffraction data, the Ge atom in tribromides 3a, (S)-3b, and 3c is pentacoordinated and has trigonal bipyramidal configuration with two halogen atoms and oxygen atom of the ether group in the equatorial positions and the halogen atom and the amide oxygen atom in the axial fragment, the bonds in which are somewhat longer as compared to the analogous bonds in tetracoordinated Ge compounds.     

Zur Chemie der 2,4-Diaminothiopyranyliumjodide Synthese von α,β,γ,δ-ungesättigten Thiocarbonsäureamiden

Aminolysis of 4-dialkylamino- and 4-alkylamino-2-methylthiothiopyranyliden iodides2 resp. under various reaction conditions leads to assymmetrically or symmetrically substituted 2,4-bisamino- or 2,4-bisdialkylamino- and 2-alkylamino-4-dialkylamino-or 2-dialkylamino-4-alkylamino- or 2-amino-4-dialkylaminodihydrothiopyranylium iodides3, 4, 5, 6 resp. On treatment with alkali 4-alkylamino- and 4-dialkylamino-2-alkylaminothiopyranylium iodides3,4 are hydrolysed to the 2-alkylimino-2H-thiopyranes7. 4-Alkylamino-2-dialkylaminothiopyranylium iodides5 react with alkali to give three products: the two stereoisomeres 2-dialkylamino-4-alkylimino-4H-thiopyranes9 A,B and theN,N-substituted α,β,γ,δ-unsaturated thiocarboxamide10. The hydrolysis of 2,4-bisdialkylaminothiopyranylium iodide6 a leads to the 2-dialkylamino-4H-thiopyran-4-one11 a, the 4-dialkylamino-2H-thiopyrane-2-one12 and theN,N-substituted unsaturated thiocarboxamide10 d. α,β,γ,δ-unsaturated thiocarboxamides10 a-c are formed by the reaction of 2-amino-4-dialkylaminothiopyranylium iodides3 a-c with diluted alkali. By heating with acids10 a-c are cyclisized to the 2-aminothiopyranylium derivates3.     

Kinetics of hydrolysis of the geminal alkoxy-NNO-azoxy compounds in sulfuric acid

The kinetics of hydrolysis of two alkoxy-NNO-azoxy compounds with geminal position of N₂O₂ groups, di(methoxy-NNO-azoxy)methane (I) and di(methyl-NON-azoxy)formal (II), as well as isomeric geminal nitramine, 2,4-dinitro-2,4-diazapentane (III) in 64.16% H₂SO₄ were studied by a manometric method. The relative rates of the hydrolysis at 80°C of compounds I?CIII and methoxy-NNO-azoxymethane (IV) were found to be equal to 4.2:77:??50000:1. The limiting stage of hydrolysis of compound I is the attack of the nucleophile on the carbon atom of the MeO group of the protonated molecule I by S _N2 mechanism. According to the parameters of the Arrhenius equation the hydrolysis of compound II proceeds more probably by the S _N1     

Synthesis, characterization, and biological evaluation of new N-glycosides derived from O-pivaloylated β-d-glucopyranosylamine

The novel synthesis of N-(2,3,4,6-tetra-O-pivaloyl-??-d-glucopyranosyl) benzo[d] oxazol-2-amine 4 was described in this study. The new compounds N-arylthioureas 3a-c and 4, along with a series of glucose-modified imines 5a-g, were evaluated for their antitumor activity against human myeloid leukemia cell lines (HL-60 cells), gastric carcinoma (BGC-823 cells), liver carcinoma (Bel-7402 cells), and oral carcinomas (KB cells). The antibacterial potency of these compounds was also determined using an inhibition zone diameter test. Although none of the compounds were active against human cancer cells, compound 4 was found to be the most active compound against Escherichia coli.     

Two novel terpyridine-based chromophores with donor-acceptor structural model containing modified triphenylamine moiety: Synthesis, crystal structures and two-photon absorption properties

Two novel terpyridine-based chromophores with D-A (D = donor, A = acceptor) structural model containing modified triphenylamine moiety (L1 and L2 ) have been conveniently synthesized via formylation and reduction in satisfactory yields, and fully characterized. The single crystals of them were obtained and determined by X-ray diffraction analysis. The relationships between structure and photophysical properties of the two chromophores were investigated both experimentally and theoretically. The measured maximum TPA cross-sections per molecular weight (δmax /MW) of the chromophores are 0.63 GM/(g mol) (L1) and 0.72 GM/(g mol) (L2), respectively, in DMF as a high polar solvent. The results indicate that the value of δmax/MW could be well tuned by the intramolecular charge transfer (ICT), which could be realized by introducing additional elecron-donor/acceptor groups.     

Synthesis and anti-viral activities of some 3-(naphthalen-1-ylmethylene)-5-phenylfuran-2(3H)-one candidates

3-(Naphthalen-1-ylmethylene)-5-phenylfuran-2(3H)-one 1 was prepared and converted into a variety of heterocyclic systems of synthetic and biological importance. Benzylamine was reacted with furanone 1 to afford compounds 2 and 3 according to the reaction conditions. Butanamide 2 was reacted with thionyl chloride or thiourea to give derivatives 4 and 5, respectively. Compound 3 was reacted with ethyl cyanoacetate to give the corresponding pyrrolopyridine derivative 6. Treatment of 1 with hydrazine hydrate afforded compounds 7 and 8 according to the reaction conditions. Also, compound 1 was reacted with phenyl hydrazine, hydroxyl amine, malononitrile or thiourea to give compounds 9–12, respectively. Cyclization of 7 with ethoxymethylene-malononitrile, ethyl-(ethoxymethylene)cyanoacetate, carbon disulphide or acetylacetone afforded the corresponding compounds 13–16, respectively. Condensation of 7 with p-nitrobenzaldehyde gave the corresponding hydrazone 17, which was treated with thioglycolic acid or chloroacetyl chloride to give compounds 18 and 19, respectively. Also, most of the prepared products were tested for anti-avian influenza virus and revealed promising antiviral activity against H5N1 virus [A/Chicken/Egypt/1/2006 (H5N1)] by determination of both TC ₅₀ and ED ₅₀ and confirmed by plaque reduction assay on MDCK cells. Compounds 7, 8, 11, 12 and 13 showed the highest effect compared with the other tested compounds.     

Synthesis and antimicrobial activity of novel chalcone derivatives

A series of novel 3-[N, N-bis(2-hydroxyethyl)-amino]-chalcone derivatives 3a–3j were synthesized by the aldol condensation of [N, N-bis(2-hydroethyl)-3-amino]-acetophenone 2 with aromatic aldehydes. Their structures were further confirmed by ESI-HRMS, ¹H NMR, IR and elemental analysis. X-ray analysis reveals crystal 3b is a monoclinic system with P2₁/n space group. The antimicrobial activities of the newly synthesized chalcones in vitro were evaluated and the results indicated that most compounds presented moderate to good antimicrobial activities, especially the antifungal capability. Compounds 3a, 3d, 3f and 3g revealed obvious potency against Candida albicans with MIC values of 32 μg/mL, which were better compared with others.     

Zur Synthese der 4-Dialkylamino-5,6-dihydrothiopyran-2-thione

4-Dialkylamino-5,6-dihydrothiopyrane-2-thiones3, 9, 10 are synthesized in good yields by reaction of α,β-unsaturated methylketones with dialkylammonium-dialkyldithiocarbamates5 or carbon disulfide and secondary amines. The reaction takes place via the corresponding oxobutyl-N,N-dialkyldithiocarbamates13 and dialkylaminobutenyl-N,N-dialkyldithiocarbamates14. Cyclohexenylmethylketone11 reacts with5 to give 4-dialkylaminohexahydrothiochromane-2-thiones12. In dimethylformamide or diethyl-formamide as solvents aminolysis take place and 4-dimethylamino or 4-diethylaminothiopyrane-2-thiones are also formed. Instead of 3-alken-2-ones6 also 4-hydroxy-2-alkanones7 and methylketones8 (such as acetone), which readily undergo the aldol condensation can be used for the preparation of thiopyrane-2-thiones.     

New N-nicotinyl and N-isonicotinyl, N′,N″-diaryl phosphorictriamides with new Er(III) complex: synthesis, spectroscopic study and crystal structures

Ten new N-nicotinyl and N-isonicotinyl phosphoramidates with formula XP(O)R₂, X?=?Nicotinamide(nia), R?=?NHCH₂Ph (1), N(CH₃)CH₂Ph (2), NHCH(CH₃)Ph (3), NH-CH₂C₄H₃O (4), NHCH₂(C₅H₄N) (5), 3-NH-C₅H₄N (6), and YP(O)R₂, Y?=?isonicotinamide(iso), R?=?NHCH₂Ph (7), N(CH₃)CH₂Ph (8), NHCH(CH₃)Ph (9), NH-CH₂C₄H₃O (10) plus one new Er(III) complex with formula Er(L)₂(NO₃)₃ (11), L?=?(iso)PO(NHCH₂C₄H₃O)₂ (10), were synthesized and characterized by elemental analysis and ¹H, ¹³C, ³¹P NMR, IR, UV?Cvis spectroscopy. Crystal structures of compounds 10 and 11 were also determined by X-ray crystallography. Interestingly, the ¹H NMR spectra of compounds 1, 2, 6, 7, 9 indicated long-range ⁿ J _P,H (n?=?5,6,7) coupling constants, in the range of 1.4?C1.9?Hz, for the splitting of pyridine ring protons with phosphorus atom. IR results showed that the ??(C=O) values of compounds 7?C10 are greater than those of compounds 1?C5 which means that isonicotinyl moiety is more electron withdrawing than nicotinyl group. X-ray outcomes revealed that in complex 11 three phosphoric triamide ligands have been connected to each Er(III); one from N_pyridine and two from P=O donor sites. One of the P=O donor ligands is mono dentate while the other one acts as a bidentate ligand and coordinates to another Er atom via its N_pyridine site. By forming complex 11 the P=O and C?CN_amide bond lengths of ligand is increased in both, mono and bi dentate, ligands while the C=O bond length is decreased to lower values. These variations are in good agreement with IR results. All H-bonds and electrostatic interactions lead to form a three-dimensional polymeric cluster in the crystal lattice of 10 and 11.     

Sterically hindered inversion of nitrogen atoms in cyclic hydrazines:N,N′-dialkyl-1,3,4-oxadiazolidines; 1,3,4-thiadiazolidine; and 4,5-benzo-1,2,3,6-tetrahydropyridazine

N,N′-Diisopropyl-substituted 1,3,4-oxadiazolidine3c, 1,3,4-thiadiazolidine6, 4,5-benzo-1,2,3,6-tetrahydropyridazine8, and new 3,4-dialkyl-1,3,4-oxadiazolidines9–14 were synthesized and studied. The configurational stability of the N atoms does not change on going from compound3c to itsS-analog6 and decreases in the case of pyridazine8. 3,4-Di-tert-alkyl-1,3,4-oxadiazolidines3d and11–14 were found to be promising objectes for optical resolution.