The efficient synthesis of aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone leuco-dye derivatives

An efficient method for the synthesis of 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone derivatives by the reaction of 2-hydroxynaphthalene-1,4-dione and aldehydes in the presence of a catalytic amount of p-toluene sulfonic acid under solvent-free conditions at 100 °C is described.     

Cage-opening supramolecular isomerism in Cu(II) complexes

Reactions of Cu(NO₃)₂·3H₂O or Cu(CF₃SO₃)₂·6H₂O with semirigid ligands 2,6-bis(pyridin-3-ylmethyl)-3a,4,4a,7a,8,8a-hexahydro-4,8-ethenopyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetraone (L1) and 2,6-bis(pyridin-4-ylmethyl)-3a,4,4a,7a,8,8a-hexahydro-4,8-ethenopyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetraone (L2) result in 0D tetragonal prismatic cage (1, 4), 1D loop-and-chain (2, 5, 6), and 2D (4,4) network (3) metal-organic complexes, which comprise of U_a, U_b or Z type ligand conformations, respectively. Solid state X-ray diffraction and solution state ESI-MS analyses manifest the ring-opening isomerization mechanism among the complexes, and photoluminescence properties are also studied.     

Regioselective synthesis and pharmacological activities of spirodibenzo[a,d]cycloheptene-5,2′-[1,3,4]thiadiazole derivatives

Some new 3^′,5^′-substituted-5H,3^′ H-spirodibenzo[a, d]cycloheptene-5,2^′-[1,3,4]thiadiazole and 10,11-dihydro-5H,3^′ H-spirodibenzo[a, d]cycloheptene-5,2^′-[1,3,4]thiadiazole derivatives 3a–n were regioselectively synthesized under 1,3-dipolar cycloaddition of 5-thiooxo-5H-dibenzo[a, d]cyclo-heptene and 5-thiooxo-10,11-dihydro-5H-dibenzo[a, d]cycloheptene with a variety of nitrilimines (generated in situ via dehydrohalogenation of the corresponding hydrazonoyl chlorides in the presence of triethylamine). The new products were tested for antiinflammatory, analgesic, and ulcerogenic score activities comparable to Indomethacin. Compounds 3i–l showed significant activity compared to Indomethacin.     

Parallel Synthesis of Pyrrolo[3,2-f]quinolines (PQQ Skeleton) Library via a One-Pot Three-Component Reaction under Catalyst-Free Conditions

An efficient and straightforward synthetic protocol was developed for the diversity-oriented synthesis of 13-aryl-6,13-dihydrochromeno[4,3-b]pyrrolo[3,2-f]quinolin- 12(3H)-one and 10-aryl-3H-furo[3,4-b]pyrrolo[3,2-f]quinolin-9(7H)-one derivatives (PQQ skeleton) in high yields under catalyst-free conditions. This procedure includes a one-pot three-component reaction of aromatic aldehyde, 1H-indol-5-amine, and 1,3-dicarbonyl compounds to generate total of 25-Membered structurally interesting and pharmacologically significant PQQ skeletons for bio-active screening.     

Semiquantitative analysis of thiophenic compounds in light cycle oil (LCO) using C NMR spectroscopy

S-methyltetrafluoroborate salts of the thiophenic compounds (CH₃-S⁺:BF₄⁻) present in LCO petroleum fractions were obtained and analyzed by ¹H and ¹³C NMR spectroscopy. The methylation of the samples was carried out using 99.5% ¹³C enriched methyl iodine, to improve the sensitivity of the technique. The amount of the methylated derivatives was determined by the internal standard method; using dioxane as a reference, 37 sulphur compounds were detected. Among them, benzo[b]thiophene, dibenzo[b,d]thiophene, and several isomers of methyl, dimethyl and trimethyl[b]benzothiophenes were the most abundant. With this research, it was demonstrated that NMR spectroscopy can be used to analyze thiophenic compounds from petroleum medium fractions.     

Molecular relaxation processes in poly(N-acryloyl-10,11-dihydrodibenz [b, f]azepine)

The preparation and homopolymerization of N-acryloyl-10,11-dihydrodibenz[b, f]azepine is described. The relaxation behaviour is characterized using dielectric relaxation, pulsed n.m.r. and thermally stimulated depolarization (t.s.d.) techniques. In order to assist the assignment of relaxation data to molecular behaviour 5-chloroacetyl and 5-propionyl derivatives of iminobibenzyl were prepared and studied by dielectric relaxation in the matrix-isolated state. Comparison with N-ethyl carbazole under similar conditions revealed the existence of a relaxation in the polymer associated with nitrogen inversion in addition to a relaxation due to the glass transition. The data may be useful in studies relating to the pharmacological activity of the dibenz[b, f]azepine ring system.     

3-D organic-inorganic hybrid architecture based on Tröger's Base: Synthesis,supramolecular structure,and aggregation-induced emission properties

An organic-inorganic hybrid solid (DMDP)[Hg(SCN)₄] (1) (DMDP = 2,8-(6H,12H-5,11-methanodibenzo[b,f]diazocineylene)-di(p-ethenyl-N-methyl-pyridinium)) was designed and synthesized. X-Ray structural analysis reveals that it comprises a 3-D interpenetrating superstructure that 1-D inorganic anionic chains {[Hg(SCN)₄]^2 −}_∞ penetrates into 2-D organic (DMDP)^2 + cationic network. Photoluminescence investigation show that compound 1 exhibits a typical aggregation-induced emission (AIE) properties.     

Synthesis and properties of cyclopentadithiophene-based poly(silarylenesiloxane) derivatives

Poly(silarylenesiloxane) derivatives with 4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene moiety, bearing dimethyl- (P1), methylphenyl- (P2) and diphenyl- (P3) substituents on silyl moieties, were prepared via polycondensation of the corresponding disilanol monomers, that is, 2,6-bis(dimethylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M1), 2,6-bis(methylphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M2), and 2,6-bis(diphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M3), respectively. P1-P3 exhibited the good solubility in common organic solvents, such as benzene, toluene, chloroform, dichloromethane, THF, and so on. The glass transition temperatures (T_gs) of P1, P2 and P3 were determined by differential scanning calorimetry to be 56, 97 and 137 °C, respectively, depending on the substituent on the silyl moieties. No melting temperatures (T_ms) of P1, P2 and P3 were observed, suggesting the obtained P1-P3 are amorphous polymers. The temperatures at 5% weight loss (T_d5s) of P1, P2 and P3 were 460, 459 and 479 °C, respectively, indicating that the larger number of phenyl group on the silyl moieties resulted in the better thermostability. Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra by introducing silyl substituents onto 4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene moiety. In addition, the bathochromic shift of the maximum absorption (λ_abs) and the increase in the fluorescence quantum yield (Φ_F) were observed by the introduction of phenyl group onto the silyl moieties.     

Synthesis and characterization of iron (III) complexes of N4 schiff base macrocycles

Iron(III) complexes of the diprotic N₄ Schiff base macrocycles, 7,8,15,16,17,18-hexahydro-dibenzo[e,m] [1,4,8,11]tetraazacyclotetradecine (H₂(2,2mac)) and 8,9,16,17,18,19-hexahydro-7H-dibenzo[e,n][1,4,8,12]tetraazacyclopentaadecine(H₂(3,2mac)), were prepared by the metathesis reaction of anhydrous iron (III) bromide with the disodium or magnesium complexes of the dianionic ligands in THF under an inert atmosphere. The complexes exhibit the intermediate spin state as evidenced by magnetic susceptibility and Mössbauer spectroscopy. Fe(3,2 mac)Br is structurally characterized as a distorted square pyramid with the four nitrogen atoms in the basal positions and the bromide occupying the axial site. The average iron to nitrogen bond distance is 1.921 Å.     

An efficient microwave-assisted synthesis of thieno[2,3- b ]quinolines under solvent-free conditions

A novel and efficient method for the synthesis of substituted thieno[2,3-b]quinolines has been developed. A simple one-pot reaction of 3-formyl-2-mercaptoquinolines 2a–l with 1-chloroacetone, 2-chloroacetamide, ethyl chloroacetate and 2-chloro-1-phenylethanone in presence of catalytic amount of potassium carbonate under microwave irradiation and solvent-free conditions gave thieno[2,3-b]quinolin-2-ylethanone derivatives 3a–e, thieno[2,3-b]quinoline-2-carboxamide derivatives 4a–e, ethyl thieno[2,3-b]quinoline-2-carboxylate 5a–e and phenyl(thieno[2,3-b]quinolin-2-yl)methanone derivatives 6a–e compounds respectively. The structures of all the newly synthesised compounds were elucidated on the basis of elemental analysis, IR, ¹H NMR and mass spectral data.     

Geometric figures with the same chord length probability density function: Six examples

The chord length probability density functions for isotropic uniform random chords f(l) have been studied for 12 different geometric figures Ki. The detailed analysis shows: six pairs of different Ki possess the same f_i(l). In greater detail, for the following six figure-pairs (specific length parameter b),1. 60°-angle with side b ↔ equilateral triangle with side length b,2. 90°-angle with side b ↔ square with side length b,3. 60°-wedge of side length b ↔ triangular rod of side length b,4. 90°-wedge of side length b ↔ square rod of side length b,5. 90°-angle with one side b, one infinitely long side e → ∞, ↔ plane stripe of breadth b,6. 90°-wedge with one breadth b, two sides of length e → ∞, ↔ infinite Layer of constant thickness b, the respective functions f_i(l,b) are identical. Thus, without additional shape information, an identification of such a figure via its chord length probability density function (PDF) is not possible. However, in all the cases considered, the length parameter b, involved in the function f(l), can be recognized from the intrinsic behavior of f(l,b).Furthermore, the agreement of the first moments of the respective functions f_i can be verified by use of the extended Cauchy theorem for non-convex figures.     

SHS of single crystals in the B-C-Mg system: Crystal structure of new modification of B25C4Mg1.42 = [B12]2[CBC][C2]Mg1.42

A new modification of B₂₅C₄Mg_1.42, [B₁₂]₂[CBC][C₂]Mg_1.42, was prepared by magnesiothermic SHS and characterized by XRD. This compound was found to have the following crystallographic parameters: a = 9.626(1), b = 11.329(1), c = 8.966(1) Å, β = 105.80(3)°, V = 940.8(2) ų, space group P2₁/b, Z = 4, R = 0.032. SHS-produced crystals exhibited high acid resistance and hardness and can be recommended as a starting compound for synthesis of other modifications of carboboride.     

Synthesis and photoluminescence properties of heterocycle-containing poly(disubstituted acetylene)s

The metathesis polymerizations of disubstituted acetylenes containing heterocycles such as thiophene, furan, benzo[b]thiophene, and benzothiazole were examined using NbCl₅, TaCl₅, and WCl₆. Thiophene-containing monomers polymerized to afford relatively high-molecular-weight polymers in moderate yields. Benzo[b]thiophene-containing monomers also polymerized to give polymers with relatively high molecular weights. On the other hand, furan- and benzothiazole-containing monomers exhibited low metathesis polymerizability, and the polymerizations did not provide high-molecular-weight polymers. Poly(1-hexyl-2-arylacetylene)s having heterocycles [poly(1a) and poly(3a), Scheme 1] emitted blue-colored lights, and the emission maxima were around 480 nm. Heterocycle-containing poly(1-phenyl-2-arylacetylene) [poly(1b)] and poly(1-fluorenyl-2-arylacetylene) [poly(3d)] showed green-colored and yellow-colored emissions, and the emission maxima were 520 and 540 nm, respectively. The emission wavelengths of poly(disubstituted acetylene)s having heterocycles were almost the same as those of the corresponding poly(disubstituted acetylene)s without heterocycles. However, heterocycle-containing polymers showed high fluorescence quantum yields compared to the corresponding polymers without heterocycles. Diarylacetylene polymers showed emission red-shifts between the solution and cast film, while the emission maximum of poly(1-hexyl-2-phenylacetylene) [poly(1a)] in the cast film was almost the same as that in the solution. Benzo[b]thiophene-containing poly(1-(4-trimethylsilylphenyl)-2-phenylacetylene) [poly(3b)] and poly(1-(9,9-dimethyl-2-fluorenyl)-2-phenylacetylene) [poly(3d)] afforded the free-standing membranes because of their high molecular weights. The oxygen permeability coefficient (PO₂) of poly(3b) was as large as 1400 barrers. Poly(3d) showed higher gas permeability, and its PO₂ was 5300 barrers.     

Intermediates and dyes for synthetic-polymer fibres. Benzo [b]naphtho [3,2-d]thiophene-6,7-dicarboxylic acid imides and benzimidazo dibenzothio

Benzo[b]naphtho[2,3-d]thiophene-6,7-dicarboxylic anhydride (I) is obtained y Pschorr intramolecular cyclisation of 2-(2-aminophenylthio)-1,8-naphthalic anhydride. Condensation with alkylamines and arylamines gives the corresponding imides, which colour synthetic-polymer fibres in greenish-yellow hues, and reaction with o-phenylenediamines affords the isomer mixtures of derivatives of benzimidazo[1,2-b]-dibenzothiopheno-[4,3,2-d,e] isoquinolin-10-one and of benzimidazo-[2,1-a] dibenzothiopheno-[4,3,2-d,e]isoqumolin-10-one, which dye polyester fibres bright reddish-orange. Both series of dyes have excellent fastness to light and sublimation. The colour of the dyes is discussed in relation to the isomeric compounds derived from benzo[k,1]thioxanthene-3,4-dicarboxylic anhydride (III) and from benzo[d]naphtho[1,2-b]thiophene-9,10-dicarboxylic anhydride (II). The synthesis of the individual isomers resulting from reaction of I with o-phenylenediamine is reported and their absorption maxima related to polar factors operative within each isomer.     

Iridium‐Catalyzed Asymmetric Allylic Etherification and Ring‐Closing Metathesis Reaction for Enantioselective Synthesis of Chromene and 2,5‐Dihydrobenzo[b]oxepine Derivatives

Iridium‐catalyzed asymmetric etherifications of allylic carbonates with 2‐vinylphenols and 2‐allylphenols were realized. With a catalyst generated from 2 mol% of [Ir(cod)Cl]₂ (cod=cycloocta‐1,5‐diene) and 4 mol% of the phosphoramidite ligand L2 , the etherification products were obtained in excellent ees and then subjected to the ring‐closing metathesis reaction providing an efficient synthesis of enantioenriched 2H‐chromene and 2,5‐dihydrobenzo[b]oxepine derivatives.     

8‐Benzyltetrahydropyrazino[2,1‐f]purinediones: Water‐Soluble Tricyclic Xanthine Derivatives as Multitarget Drugs for Neurodegenerative Diseases

8‐Benzyl‐substituted tetrahydropyrazino[2,1‐f]purinediones were designed as tricyclic xanthine derivatives containing a basic nitrogen atom in the tetrahydropyrazine ring to improve water solubility. A library of 69 derivatives was prepared and evaluated in radioligand binding studies at adenosine receptor (AR) subtypes and for their ability to inhibit monoamine oxidases (MAO). Potent dual‐target‐directed A₁/A_2A adenosine receptor antagonists were identified. Several compounds showed triple‐target inhibition; one of the best compounds was 8‐(2,4‐dichloro‐5‐fluorobenzyl)‐1,3‐dimethyl‐6,7,8,9‐tetrahydropyrazino[2,1‐f]purine‐2,4(1H,3H)‐dione ( 72 ) (human AR: K_i A₁ 217 nM , A_2A 233 nM ; IC₅₀ MAO‐B: 508 nM ). Dichlorinated compound 36 [8‐(3,4‐dichlorobenzyl)‐1,3‐dimethyl‐6,7,8,9‐tetrahydropyrazino[2,1‐f]purine‐2,4(1H,3H)‐dione] was found to be the best triple‐target drug in rat (K_i A₁ 351 nM , A_2A 322 nm; IC₅₀ MAO‐B: 260 nM ), and may serve as a useful tool for preclinical proof‐of‐principle studies. Compounds that act at multiple targets relevant for symptomatic as well as disease‐modifying treatment of neurodegenerative diseases are expected to show advantages over single‐target therapeutics.     

Synthesis of some new fused thiopyrano[2,3-d]thiazoles and their derivatives

A series of some new fused thiopyrano[2,3-d]thiazole derivatives have been synthesized by a stereo-selective hetero-Diels-Alder reaction of 5-(2,4-dihydroxy-benzylidene)-4-thioxo-thiazolidine derivatives 3a,b with acrylonitrile, ethyl acrylate, N-phenylmale-imide, ω-nitrostyrene and N-phenyl-1, 3, 4-triazole-2,5-dione. 5-Amino-9-hydroxy-dihydro-benzopyrano[3′,4′:4,5]thiopyrano[2,3-d]thiazol-6-one derivatives 14a,b have been synthesized by Michael addition of 3a,b with malononitrile. Structures and conceivable mechanisms are discussed.     

Synthesis and characterization of per-substituted spermine-bridged cyclophosphazene derivatives: the first example of syn/anti conformational polymorphism in a bridged cyclophosphazene

The synthesis and characterization of a series of per-substituted spermine-bridged cyclophosphazene derivatives are reported based on the known compound [N₃P₃X₄(NHCH₂CH₂CH₂N)CH₂CH₂]₂, (1a) (where X = Cl), to give a number of new compounds (1b–1h) in which X = OPh, [spiro-O(CH₂)₃O]_0.5, OCH₂CF₃, NHPh, NC₄H₈, Ph and NHBu^t, respectively. Two synthetic routes were utilized: (i) using the chloro-precursor 1a in nucleophilic substitution reactions with a variety of anionic and neutral nucleophiles to give compounds 1b–1f and (ii) reaction of spermine with the appropriate di-gem tetrasubstituted cyclophosphazene to give compounds 1g and 1h. Bridged compounds such as 1a–1h may exist as syn or anti conformers in the solid state and the first example of syn and anti conformational polymorphism is reported for a bridged cyclophosphazene, viz. for compound 1a.     

1D Ladder-Like Structure Motif Assembled from Edge-Sharing Rhombic Squares of Sm2Mo2 Based on [Mo(CN)8]4− and Sm3+ Ions as Building Blocks

Novel bimetallic 4d–4f complex, {Cs[Sm(MeOH)₃(DMF)(H₂O)Mo(CN)₈] · H₂O} _n (1) (DMF = N,N′-dimethylformamide) has been synthesized and structurally characterized. The crystal analyses shown that 1 exhibit a one-dimension (1D) infinite chain structure, which adopts a 1D ladder-like structure motif assembled from edge-sharing rhombic squares of Sm₂Mo₂, and that is the first structurally characterized example of a 1D ladder structure based on the [Mo(CN)₈]^4? and Sm³⁺ building blocks. The complex 1 crystallizes in triclinic, space group P-1, with a = 9.905(2), b = 10.333(2), c = 13.562(3) Å, α = 82.00(3)°, β = 86.62(3)°, γ = 65.76(3)°, V = 1253.5(4) Å³ and Z = 2. The magnetic behavior of 1 has also been studied in this paper.     

A theoretical investigation on the electronic and optical properties of π-conjugated copolymers with an efficient electron-accepting unit bithieno[3,2-b:2′3′-e]pyridine

One of the drawbacks for light-emitting diodes based on polyfluorene and derivatives (PFs) is the injection of electrons from the cathode due to the low electron affinity (EA) of most derivatives. Substitution by electron-accepting charge carriers on the conjugated polymer's backbone produces a remarkable influence on its electronic and optical properties. In this contribution, we apply quantum-chemical techniques to investigate a family of π-conjugated polymers poly(fluorene-alt-co-bithieno[3,2-b:2′3′-e]pyridine) (PFBTP) and poly(indenofluorene-alt-co-bithieno[3,2-b:2′3′-e]pyridine) (PIFBTP). The electronic properties of the neutral molecules, HOMO-LUMO gaps (Δ_H-L), in addition to the positive and negative ions, are studied using B3LYP functional. The lowest excitation energies (E_g) and the maximal absorption wavelength (λ_abs) of PFBTP and PIFBTP are studied employing the time dependent density functional theory (TD-DFT) and semiempirical method ZINDO. The IP, EA and λ_abs of the polymers were also obtained by extrapolating those of the oligomers to the inverse chain length equal to zero (1/n=0). Especially, the influence of the presence of bithieno[3,2-b:2′3′-e]pyridine (BTP) groups on to the fluorene or indenofluorene moieties on the electron-accepting and -transporting is emphasized. As shown the BTP is a good electron-accepting moiety for electronic materials due to the presence of the three electron negative heteroatoms. For both PFBTP and PIFBTP, the LUMOs are significantly lower about 0.6 eV than that of their corresponding polyfluorene (PF), which results in the increasing of EAs by about 0.6 eV than PF, indicating that the bithieonpyridine units have significantly improved the electron-accepting properties of the copolymers. These cause the band gap narrower and the maximal absorption red-shifted comparing with PF.