The structure and thermal properties of novel DOPO-containing 1,3-benzoxazines

Three DOPO (9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide)-containing benzoxazin (3a–3c) were successfully prepared from 2-hydroxybenzaldehyde, p-substituted aniline, and DOPO by a three-step procedure. Since the phosphorus and the adjacent aliphatic carbon are both chiral centers, two pairs of enantiomers exist in 3a, 3b, or 3c. Compound 3a′, which is a pair of enantiomers existing in 3a, was isolated using recrystallization in ethyl acetate solvent. All the structures were confirmed by FT-IR, NMR, and MS spectra. The X-ray analysis indicated that the 3a′ is the RR/SS enantiomers and belongs to the monoclinic crystal system, its space group being P2₁/c. The thermal properties were investigated by DSC and TG. It has been found that the peak temperature of thermally induced ring-opening reaction was around 260–270 °C. Compounds (3a–3c, 3a′, and 3c′) had two similar thermal processes from 50 to 600 °C in TG, whereas the compound 3b′ had three thermal processes. The char yields of 3a–3c were 18.10, 16.84, and 16.34 %, respectively, while those of 3a′–3c′ were 26.00, 31.80, and 19.21 %, respectively. The results indicated that compounds 3a′–3c′ had better char properties than 3a–3c.     

Synthese,Kristallstruktur und Konformation vontrans-[2.2](1,2)Ferrocenophan und seinen 1-Hydroxyderivaten

Starting from1-(dimethylaminomethyl)-2-iodo-ferrocene (3) [2.2](1,2)ferrocenophane (2) was prepared in an 8-step synthesis with 17% overall yield. Both from the oxoderivative12 and the ferrocenophane2 puretrans-isomers (12b and2b, resp.) were obtained; the former (12b) was reduced to a separable mixture ofexo andendo 1-hydroxy-ferrocenophanes13a andb, resp. (～ 3:7), the configurations of which were assigned by the LIS-method. X-ray crystal structure analysis of2b revealed a centrosymmetrical chair conformation. From¹H- and¹³C-NMR spectra both for2b and for the hydroxyderivatives13 a rigidexo-exo chair conformation was deduced.     

Chemie des 5,7-Dihydroxy-2H-thiopyrano[2,3-b]pyridin-4(3H)-ons

Hydrolysis of the 4-alkyliminothiopyrano[2,3-b]pyridinedioles (5) and 4-alkylaminothiopyrano[2,3-b]pyridones (6) resp. with 10% NaOH gives 5,7-dihydroxy-2H-thiopyrano[2,3-b]pyridine-4(3H)-one (7).7 can be obtained in better yield by reaction of 4-dimethylamino-2(1H)-pyridinethione (8) with bistrichlorphenylethylamlonate (2). Aminolysis of7 affords the two isomeric products5 and6. On treatment with hydrazines,7 reacts only to 4-hydrazonoderivatives5. By heating in bromobenzene5d is cyclisized to 1H-5,1,2,6-thiatriaza-acenaphthylen-7-ol (11). On methylation with methyljodide5,6 and7 furnish the 7-methoxyproducts13,14 and12. By heating in 20% NaOH7 is transformed into the 2-thioxo-3-pyridylmethylketone16 A and its tautomer, 2-mercapto-3-pyridylmethylketone16 B. The structures of5,6 and7 are discussed.     

Rapid simultaneous determination of 15 nucleosides and nucleobases in marine medicinal organism Anthopleura lanthogrammica Berkly by micellar electrokinetic capillary chromatography

In this study, a rapid and reliable micellar electrokinetic capillary chromatography (MECC) method has been developed and validated for the separation and quantification of 15 nucleosides and nucleobases in a kind of marine medicinal animal Anthopleura lanthogrammica Berkly. Factors such as micelle concentration, pH, concentration of buffer, etc. were investigated in order to obtain the optimum conditions for the separation. The optimized separation procedure employed 25 mM disodium hydrogen phosphate buffer containing 70 mM sodium dodecyl sulfate (SDS) at pH 8.7 as background electrolyte, 25°C of capillary temperature and 20 kV of separation voltage. UV detection was at 260 nm and injection was hydrodynamic at 50 mbar for 3 s. The whole analysis was completed within 13 min. The relative standard deviations (RSDs) of the peak areas for method precision ranged from 1.4 to 7.6%, and the recovery was between 80.2 and 112.9%. The limit of detection (LOD) for 15 nucleosides and nuleobases was between 0.25 and 0.75 μg/mL. According to the evaluation study, the method was shown to be precise, accurate and reproducible. The proposed MECC method was successfully applied for determination of nucleosides and nucleobases in Chinese Anthopleura lanthogrammica Berkly. The result showed that the species and content of nucleosides and nucleobases in Anthopleura lanthogrammica Berkly samples were abundant.     

Synthese von 1-substituierten 4-Amino-2(1H)-pyridinthionen durchDimroth-Umlagerung aus 2,4-Diaminothiopyranyliumhalogeniden

4-Amino-2-alkylimino-2H-thiopyranes (5) and 4-amino-2-alkylaminothiopyranylium halogenides (4) resp. on heating in refluxingDMFA are rearranged in the presence of Na-ethylate to 1-alkyl-4-aminodihydro-2(1H)-pyridinethiones (2). Also 2-methylthiothiopyranylidenammonium iodides (6) and 2-methylthio-4H-thiopyrane-4-one (7) can be transformed into 1-substituted 2(1 H)-pyridinethiones (2) by heating in prim. amines. On treatment with alkali. 4-dimethylaminothiopyranylium iodide (4 a) is transformed into its base5 a and hydrolyzed to8. 5a and8 are rearranged to the pyridinethiones2 a and the tautomers9 A,B. The structure of the rearranged pyridinethiones2 was proved by the1-phenylderivate2 a. Thus 4-methyl-3-penten-2-on reacts with phenylthiourea via the phenylimino-1,3-thiazine (14) to give 3-phenyl-2(1H)pyridinethione (15).15 is transformed by themethylpyrimidine-pyridine-rearrangement to the 1-phenylpyridinethione2 a. The mechanism of theDimroth-reaction of 2-alkylimino-2H-thiopyranes (5) and the stereochemistry of the1-benzyl-6-phenyl-2(1H)-pyridinethiones2 are discussed.     

Über Reaktionen mit Betainen, 18. Mitt. Über Betaine und ihre Beziehungen zu N-Yliden. Trifluoracetyl-N-methylide und ihre Beziehungen zu den entsprechenden Ammoniumbasen

The betaines1b–d were prepared⁴ by systematic variation of the alkyl groups and were reacted with trifluoroacetic acid anhydride (TFA) to give the diacyl-ylides2b,c. The betain1d andTFA afford the trifluoroacetate3d ⁵. The salts3b,c, which result from hydrolysis of2b,c as well as3d (X=I) can be transformed in 75 to 83% yield into the monoacyl-ylides4b–d with the help of silver oxide. Aqueous solutions of4a–d exhibit alkalinepH, which points to the formation of the corresponding ammonium bases. In the case of4b,c the bases5b,c could be isolated. It can be shown, that4b,c and5b,c, respectively, undergo a reversible addition or elimination of one mole wather with great ease.     

Conformational space of tetrakis(2-naphthalenyl)ethene: a naphthologous AIE luminogen

The AIE luminogen tetrakis(2-naphthalenyl)ethene (2-NA ₄ E) was synthesized by Barton’s double extrusion diazo-thione coupling method from 2,2′-dinaphthyl thioketone and 2,2′-(diazomethylene)bisnaphthylene in 77 % yield. The structure of 2-NA ₄ E was confirmed by its ¹H NMR and ¹³C NMR spectra with full assignments. 2-NA ₄ E and its parent tetraphenylethene (Ph ₄ E) have been subjected to a comprehensive computational DFT study, in search of their conformational spaces. Seven conformers and two transition states of 2-NA ₄ E have been located. Four conformers and one transition state of Ph ₄ E have been located. The conformers of 2-NA ₄ E and Ph ₄ E are not overcrowded, as indicated by the contact distances in the fjord and cove regions. The relative free energies (ΔG ₂₉₈) of the six most stable conformers of 2-NA ₄ E are in the narrow range of 2.3 kJ/mol; they make comparable contributions (12–29 %) to the equilibrium mixture. The energy barriers for the diastereomerization D ₂-Z,Z,Z,Z $ \rightleftharpoons $ ? D ₂-E,E,E,E via the transition state C ₁-Z,E,E,Z and for the enantiomerization C ₂-Z,Z,E,E $ \rightleftharpoons $ ? C ₂-E,E,Z,Z via the transition state C _i -Z,E,Z,E are only 29.8 and 29.0 kJ/mol, respectively, indicating very rapid rates of diastereomerization and enantiomerization at room temperature. The values of naphthalenyl torsion angles and ethenic twist angles in 2-NA ₄ E are almost identical to those in the parent Ph ₄ E. The previously proposed “bulkiness” of the naphthalenyl substituents and the validity of the restriction of naphthalenyl rotation are challenged. The analysis of the AIE effect in 2-NA ₄ E should take into account the intermolecular homochiral and heterochiral interactions between the conformers.     

Autoassembly of cage structures

Thed,l-(1a) andmeso-forms (1b) of α,α'-dihydroxy-α,α'-dimethyladipic acid, dilactone (3), diiminodilactone (4), and lactonolactam (5) were obtained by the reaction of acetonylacetone with KCN and HCl. The transformations of1 to the esters2, dilactone3 to la, and diiminodilactone4 to dilactone3 were studied. It was shown that3 can be readily obtained from la by thermolysis, acid catalysis, and DCC action as well as by acid catalyzed cyclization of2a, while dilactone3 can be obtained from1b and2b in negligible yield only under drastic conditions, obviously, due to the partial epimirization of themeso-forms. The mild thermolysis of1b leads totrans-lactonoacid (6), from which the ester7 has been obtained. The effective acid catalyzed cyclization of amides8 and9 to3, lactamoamide12 to5, and amide14 to model lactone13 was found. The NMR spectra of the products were studied, and a¹H NMR test was suggested for identification ofd,l- andmeso-forms1 and2. The stereochemistry of monolactones6, 7, 9, 10a, 10b, 11, and dilactone3 was established. The differences in the chemical behavior of α,α'-dihydroxyglutaric and adipic acids were explained by the significant reduction of the non-bonded interactions of the substituents in the corresponding monolactones during the transfer from 1,3- to 1,4-substituted systems.     

Syntheses and extraction properties of novel biscalixarene and thiacalix[4]arene hydrazone derivatives

By reacting thiacalix[4]arene with p-tosyloxyethoxylbenzaldehyde 1, 3-bis(benzaldehyde-4-oxyethyloxy)-p-tert-butylthiacalix[4]arene (2) were prepared in yield of 65%. Refluxing compound 2 with aniline, salicylic hydrazide, nicotinic hydrazide and isonicotinic hydrazide, novel ringopening 1,3-bis-arylformyl-hydrazone substituted thiacalix[4]arene derivatives (3a–3d) were obtained in yields of 77–89%. Refluxing compound 2 with o-phenylendiamine, oxalyl dihydrazide, malonic dihydrazide and adipic dihydrazide in “1 + 1” intermolecular condensation mode under diluted condition, novel 1,3-bis-acyl hydrazone-bridged calix[4]arene derivatives (4a–4d) were prepared in good yields. Moreover, by condensating compound 2 with 1,3-bis(hydrazinocarbonyl-methoxy)-p-tert-butylcalix[4]arene (5), the first example of hydrazone-bridged biscalixarene (6) with calix[4]arene and thiacalix[4]arene subunits was facilely synthesized in yield of 90%. The noncompetitive and competitive extracting experiments showed that these novel hosts were good receptors for both metal cations and α-amino acids. Compounds 3a–3d and 4a–4d showed similar binding properties with high extraction percentage but low extracting selectivities. Biscalixarene 6 exhibited not only high extracting abilities but also good extracting selectivities.     

Stereochemie von α,ω-Diphenyl-alkan-α,ω-diolen

Reduction (both catalytically and with complex hydrides) of the diphenyl diketones1 (a, b, c andd withn=0, 2, 3 and 4) was investigated mainly with regard to the diastereomeric ratio of the diols2. For2 a and2 b exact results were obtained by NMR spectroscopy (without or with shift reagents) of the diol mixture (2 a) or after stereoselective cyclization to the cyclic ethers (3 b). AlsoGC andLLC were employed for the analysis of2 a (GC of the trimethylsilyl derivatives) and for the ethers3, resp. (GC for3 a and3 d;LLC for3 b and3 c). The reduction of1 a, 1 b (and in part1 c) proceeds with high stereoselectivity; themeso-diol preponderates in the case of2 a, therac.-diol for2 b and2 c; with increasingn the diastereomeric ratio approaches the statistical ratio of 1∶1. Preparations of the stereoisomeric diols (2 b, c andd via acetylenic precursors) and of the cyclic diphenyl ethers (by stereoselective cyclization and/or chromatographic separation;3 c and3 d for the first time) as well as the determination of their configurations are described. The latter was achieved by NMR and for the ethers3 also by hydrogenation of the corresponding heteroaromatics.     

Electrochemical determination of acetaminophen in the presence of propranolol using an electrode modified with a Schiff base from 2-hydroxy-1-naphthaldehyde and ethylenediamine and multi-walled carbon nanotubes

A carbon paste electrode, modified with N,N′-bis-(2-hydroxy-1-naphthalidene)ethylenediamine and multi-walled carbon nanotubes (HNED-MWCNPE), was used for the determination of acetaminophen (ACOP) and propranolol (PP). Cyclic voltammetry (CV), chronocoulometry, chronoamperometry and differential pulse voltammetry (DPV) techniques were employed to study electro-oxidation of ACOP. The results revealed that the modified electrode showed an electrocatalytic activity toward the anodic oxidation of acetaminophen by a marked enhancement in the current response in buffered solution at pH 8.0. Some kinetic parameters such as the electron transfer coefficient (α) were also determined for the ACOP oxidation. The linear concentration range of 1 × 10^?3?1 × 10^?6 M with a detection limit of 4.6 × 10^?8 M (n = 16) for ACOP was obtained using DPV (pH 8.0). The modified electrode shows good sensitivity, selectivity and stability. The prepared electrode was also applied for the determination of ACOP in human blood serum.     

Copper complexes of two isomeric NS2-macrocycles

Two isomeric NS₂-macrocycles incorporating a xylyl group at ortho (o -L) and meta (m -L) positions were employed and their copper complexes (1?C5) were prepared and structurally characterized. The copper(II) nitrate complexes [Cu(L)(NO₃)₂] (1: L = o -L, 2: L = m -L) for both ligands were isolated. In each case, the copper center is five-coordinated with a distorted square pyramidal geometry. Despite the overall geometrical similarity, 1 and 2 show the different ligand conformation due to the discriminated packing pattern. Reaction of o -L with copper(II) perchlorate afforded complex 3 containing two independent complex cations [Cu(o -L)(H₂O)(DMF)(ClO₄)]⁺ and [Cu(o -L)(H₂O)(DMF)]²⁺; the coordination geometry of the former is a distorted octahedron while the latter shows a distorted square pyramidal arrangement. In the reactions of copper(I) halides (I or Br), o -L gave a mononuclear complex [Cu(o-L)I] (4) with a distorted tetrahedral geometry, while m -L afforded a unique exodentate 2:1 (ligand-to-metal) complex [trans-Br₂Cu(m-L)₂] (5) adopting a trans-type square-planar arrangement.     

Naphthologs of overcrowded bistricyclic aromatic enes: (E)-bisbenzo[a]fluorenylidene

(E)-11H-Bisbenzo[a]fluorenylidene (E-6) was synthesized by Barton’s double extrusion diazo-thione coupling method from 11H-benzo[a]fluoren-11-thione (11) and 11-diazo-11H-benzo[a]fluorene (13). The reaction is probably thermodynamically controlled; in the event that the less stable Z -6 is also formed, it would rapidly undergo Z → E diastereomerization to give E -6. The B3LYP/6-311G(d,p) calculated diastereomerization barrier for Z -6 → E -6 is ΔG ₂₉₈ = 57.0 kJ/mol (13.6 kcal/mol). The calculated equilibrium constant K _eq(E -6 → Z -6) = 92:8 (at 298 K) is indicative of a marked diastereoselectivity of the reaction leading to E -6. The structure of E-6 was established by ¹H-NMR and ¹³C-NMR spectroscopies and by X-ray analysis. PAE E-6 crystallizes in the monoclinic space group C2/c. The unit cell of the crystal structure E -6 contains eight molecules, arranged as four pairs of enantiomers. PAE E -6 adopts a twisted conformation with the pure twist of the central C¹¹=C^11′ bond ω = 39°. The dihedral angle ν in E -6 is 60.6°, which is significantly higher than the respective dihedral angle in PAEs Z -6, 2, E -7, Z -7, 14, and 15. The large syn-pyramidalization angles at C¹¹ and C^11′ (χ = 12.6° and 14.8°) of E-6 indicates the enhanced strain in the fjord regions of the molecule. The enhanced twist is primarily attributed to the double benzo[a]annelation of the bifluorenylidene moiety at the fjord regions. The B3LYP/6-311G(d,p) calculated structure of E -6 is in a very good agreement with the experimental X-ray structure. PAE E -6 adopts a twisted conformation in solution, with the downfield chemical shift of H¹/H^1′ (8.31 ppm); H¹⁰/H^10′ (δ = 7.20 ppm) and H⁹/H^9′ (δ = 6.86 ppm) in E -6 are positioned above the planes of the opposing naphthalene rings. PAEs E -6 and Z -6 are significantly higher in energy than their corresponding benzo[b]annelated isomers E -7 and Z -7.     

Donor-acceptor conjugated cooligomers for single molecule solar cells

Five novel donor-acceptor(D-A) conjugated cooligomers(F4B-hP,F5B-hP,F5B2[1,2]-hP,F5B2[1,3]-hP and F7B2[1,2]-hP) were synthesized.The absorption spectra of the cooligomers cover a wide range from 300 nm to 630 nm.The cooligomers could form films featured by alternating D-A lamellar nanostructures with the periods relative to the molecular lengths after thermal annealing or solvent vapor annealing.Single molecule solar cells were fabricated,and F5B-hP exhibited the best device performance.When the film of F5B-hP was thermally annealed,a power conversion efficiency(PCE) of 1.56% was realized.With solvent vapor annealing,the PCE could be further improved to 1.72% with a short-circuit current(J SC) of 5.76 mA/cm 2,an open-circuit voltage(V OC) of 0.87 V and a fill factor(FF) of 0.34.     

Synthesis and antimicrobial of some new substituted tetrazolomethylbenzo[d]-[1,2,3]triazole derivatives using 1H-benzo[d][1,2,3]triazole as starting material

A series of tetrazolomethylbenzo[d][1,2,3]triazole derivatives (2–14) have been synthesized and evaluated as antimicrobial agents from 1H-benzo[d][1,2,3]triazole (1) as starting material. The reaction of benzotriazole 1 with chloroacetonitrile afforded 2-(1H-benzo[d][1,2,3]-triazol-1-yl)acetonitrile 2, which was reacted with sodium azide to give tetrazole derivative 3. Esterification of benzotriazole 1 with ethyl bromoacetate in the presence of anhydrous potassium carbonate afforded ester 4, which was treated with hydrazine hydrate to afford the corresponding hydrazide 5. Reaction of 3 with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide afforded the nitro-glycoside derivative 6, which was deacetylated using methanolic ammonia to deprotected nitroglycoside 7. The hydrazide 5 was reacted with 4,5,6,7-tetrachlorophthalic anhydride or 1,2,4,5-benzenetetracarboxylic dianhydride in refluxing glacial acetic acid to give the corresponding imides 8 and 9, respectively. Also, the hydrazide 5 was reacted with carbon disulphide in ethanol to give potassium salt 10, which was reacted with hydrazine hydrate to afford aminotriazole derivative 11. The latter compound was reacted with carbon disulphide to afford thiadiazole derivative 12, which was treated with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide to give the thioglycoside derivative 13. Deacetylation of the thioglycoside 13 using methanolic ammonia solution at room temperature afforded the deprotected thioglycoside 14. The antimicrobial screening of some synthesized compounds showed that many of these compounds have good antimicrobial activities comparable to streptomycin and fusidic acid as reference drugs.     

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.     

The first example of asymmetric Michael reaction catalyzed by chiral alkali metal alkoxides

Some chiral sodium alkoxides can be used as catalysts in the asymmetric Michael reaction as exemplified by the 1,4-addition of an achiral Ni^II complex of the Schiff base derived from glycine andN-(2-pyridylcarbonyl)-o-aminobenzophenone (1) to methyl methacrylate (2) or methyl acrylate (14). The products of the reaction of1 with2,viz., the corresponding diastereomeric complexes of 4-methylglutamic acid, are formed in dissimilar amounts (de 26–85%); theee value for the major diastereomer (2S,4R)-3a is 28%. After recrystallization, the enantiomeric purity of complex3a increases toee>85%. Acidcatalyzed hydrolysis of the enantiomerically enriched complex3a affords (2S,4R)-4-methylglutamic acid (ee>85%). The complex of glutamic acid15 resulting from the reaction of1 with14 is formed with anee of 45%. After recrystallization, the enantiomeric purities of complex15 and glutamic acid increase toee>90%.     

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 of (zinc(II) phthalocyanine)-containing cellulose derivative using phthalocyanine-ring formation reaction

2,3-Di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) cellulose (5) was synthesized from cellulose (1) by five reaction steps via 6-O-(3′,4′-dicyanophenyl)-2,3-di-O-myristyl cellulose (4). The key reaction was phthalocyanine-ring formation on a cellulose backbone, that is, the reaction of compound 4 with o-phthalodinitrile in the presence of hexamethyldisilazane and zinc acetate in DMF afforded to compound 5 in 35.4 % yield. Consequently, the degree of substitution with phthalocyanine moieties of compound 5 was 0.38. The LB monolayer film of compound 5 on an indium tin oxide (ITO) electrode was found to show photocurrent generation performance at 680 nm.     

The electronic structure of 5-methylhexa-1,2,4-triene-1,3-diyl, the first representative of highly delocalized triplet ethynylvinylcarbenes, from ESR spectroscopy data and quantum chemical calculations

The ESR spectrum of the first representative of highly conjugated triplet ethynylvinylcarbenes, 5-methylhexa-1,2,4-triene-1,3-diyl (1), was recorded in solid argon matrix. The zero-field splitting (ZFS) parameters of carbene 1 (D = 0.5054±0.0006 cm^?1 and E = 0.0045±0.0002 cm^?1) determined from the experimental ESR spectrum are in between the corresponding parameters of ethynylcarbene C3H2 (2) and vinylcarbene C₃H₄ (3): D(3) < D(1) < D(2) and E(2) < E(1) < E(3). Quantum chemical calculations of the ZFS parameters of 1, 2, and 3 have been carried out for the first time using two DFT-based approaches, RODFT and UDFT. An analysis of the experimental and theoretical ZFS parameters shows that carbene 1 is characterized by a greater extent of delocalization of the spin density of unpaired electrons than carbenes 2 and 3. The characteristic structural fragments of carbene 1 possess the principal features of the electronic structure of both ethynylcarbene (2) and vinylcarbene (3), respectively. Magnetic spin-spin interactions are identical in carbenes 1 and 2. The dominant contribution to D in 1 and 2 results from the one-center spin-spin interactions on carbon atoms in the propynylidene group, which are subjected to strong spin polarization.