Theoretical studies on the role of pi-electron delocalization in determining the conformation of N-benzylideneaniline with three types of LMO basis sets

To understand the role of pi-electron delocalization in determining the conformation of the NBA (Ph-N==CH-Ph) molecule, the following three LMO (localized molecular orbital) basis sets are constructed: a LFMO (highly localized fragment molecular orbital), an NBO (natural bond orbital), and a special NBO (NBO-II) basis sets, and their localization degrees are evaluated with our suggesting index D(L). Afterward, the vertical resonance energy DeltaE(V) is obtained from the Morokuma's energy partition over each of three LMO basis sets. DeltaE(V) = DeltaE(H) (one electron energy) + DeltaE(two) (two electron energy), and DeltaE(two) = DeltaE(Cou) (Coulomb) + DeltaE(ex) (exchange) + DeltaE(ec) (or SigmaDeltaE(n)) (electron correction). DeltaE(H) is always stabilizing, and DeltaE(Cou) is destabilizing for all time. In the case of the LFMO basis set, DeltaE(Cou) is so great that DeltaE(two) > |DeltaE(H)|. Therefore, DeltaE(V) is always destabilizing, and is least destabilizing at about the theta = 90 degrees geometry. Of the three calculation methods such as HF, DFT, and MPn (n = 2, 3, and 4), the MPn method provides DeltaE(V) with the greatest value. In the case of the NBO basis set, on the contrary, DeltaE(V) is stabilizing due to DeltaE(Cou) being less destabilizing, and it is most stabilizing at a planar geometry. The LFMO basis set has the highest localization degree, and it is most appropriate for the energy partition. In the NBA molecule, pi-electron delocalization is destabilization, and it has a tendency to distort the NBA molecular away from its planar geometry as far as possible.     

Theoretical study of changes in pi-electron delocalization in the analogues of an ortho-hydroxy schiff base when the proton is replaced with Li+ or BeH+

Molecular geometries of ortho-hydroxy Schiff base in keto-enamine and enol-imine tautomeric forms, its anion, and their derivatives in which H+ was replaced with Li+ or BeH+ were optimized at the B3LYP/6-311+G level of theory. Isodesmic reactions for estimating delocalization due to H-bonding or cation chelating were calculated. Geometry-based aromaticity index HOMA and magnetism-based NICS1(zz) index were used to estimate pi-electron delocalization. Keto-enamine tautomer exhibits low aromaticity in the ring and a relatively high pi-electron delocalization in the quasi-ring. The reverse was found for enol-imine tautomer. The Li+ and BeH+ derivatives showed a relatively high pi-electron delocalization in the ring and in the quasi-ring. This may be interpreted by an extension of the electron delocalization path in the pi-electron system through low-lying unoccupied p-type orbitals of Li+ and BeH+ cations.     

Novel expanded porphyrinoids with multiple-inner-ring-fusion and/or tunable aromaticity

Novel expanded porphyrinoids with advanced structure features(such as multiple-inner-ring-fusion)have a wide range of benefits(such as multi-metal coordination and facile tunable aromaticity) not offered by their normal porphyrin analogues,and have found wide applications as sensors,fluorescent probes,novel ligands and functionalized NIR organic dyes in various research fields.However,the structures of these expanded porphyrinoids are scarce due to their limited synthetic accessibility.Herein,we summarized the lately reported efficient synthesis of novel expanded porphyrinoids with multipleinner-ring-fusion(up to six-inner-ring-fusion) and smaragdyrins with tunable aromaticity.Their synthesis is either based on an oxidative ring cyclization on linear/macrocyclic oligopyrroles containing N-confused pyrrole unit(s) or a straightforward double SNAr reaction on readily available 3,5-dibromoBODIPY,respectively.     

7-N,7'-N'-(1",2"-Dithianyl-3",6"-dimethylenyl)bismitomycin C: synthesis and nucleophilic activation of a dimeric mitomycin

Dimeric alkylating agents that modify complementary DNA strands have engendered significant interest. We have prepared the novel dimeric mitomycin, 7-N,7'-N'-(1",2"-dithianyl-3",6"-dimethylenyl)bismitomycin C (9), in which the mitomycins are bridged by a dithiane unit. Dimer 9, like the clinically tested acyclic disulfides KW-2149 (3) and BMS-181174 (4), was designed to activate under nucleophilic and reductive conditions. Successive nucleophile-mediated disulfide cleavage transformations of 9 are expected to generate thiol species ideally positioned to render the two mitomycin systems vulnerable to nucleophilic attack and permit DNA interstrand cross-link formation. The dithiane linker, strategically positioned between the two mitomycins, distinguished 9 from 3 and 4. Nucleophilic activation of this cyclic disulfide permitted both activated mitomycins to remain tethered to one another. We report the synthesis of 9, and show that the nucleophile Et(3)P markedly enhances the activation and consumption of 9, compared with the reference compound 7-N, 7"-N'-(cyclohexanyl-trans-1",4"-dimethylenyl)bismitomycin C (27). We further demonstrated that provides higher levels of DNA interstrand cross-links than either the dimeric reference compounds, and 7-N,7-N'-(2",5"-dihydroxy-1",6"-hexanediyl)bismitomycin C (28), or the monomeric mitomycins, 1 and 3, when Et(3)P is added to solutions containing EcoRI-linearized pBR322 DNA.     

Torquoselective 6pi-electron electrocyclic ring closure of 1-azatrienes containing acyclic chirality at the C-terminus

Torquoselective pericyclic ring closures of 1-azatrienes that contain acyclic chirality at the C-terminus are described herein. [reaction: see text]     

Novel synthesis of porous carbons with tunable pore size by surfactant-templated sol-gel process and carbonisation

Surfactant-templated sol-gel polymerisation was explored to synthesize the resorcinol-formaldehyde (RF) gels without supercritical drying step, which were further carbonised to obtain porous carbons of a tunable pore size.     

Charge transfer complexes of some anilides with nitrobenzene derivatives as pi-electron acceptors

The charge transfer complexes formed between some anilides and pi-electron acceptors [picric acid, 2,4-dinitrophenol, 3,5-dinitrobenzoic aicd, 3,5-dinitrosalicylic acid and m-dinitrobenzene] are synthesized and characterized. Spectral characteristics and stability of the complexes are investigated and discussed in terms of donor molecular structure, pi-acceptor electron affinity, and solvent polarity. It is deduced that the complexes are mainly of the n-pi* and pi-pi* type where the ground state wave function can be described primarily by the non-bonding structure. The optimum conditions favouring the formation of the coloured complexes are extensively studied for the microdetermina-tion of anilides derivatives in pharmaceutical drugs using nitrobenzene as acceptor; the molecular structure was found to be 1:1 (D:A). Beer's law is obeyed up to 23.0, 18.60 and 16.0 micrograms ml-1 for p(OH), p-(OCH3), and p-N(CH3)2, respectively.     

Synthesis of a Novel Diamine 4-[(4''''-Butoxyphenoxy)carbonyl]phenyl-3",5"-diaminobenzoate and Corresponding Polyimides

A novel diamine 4-[(4'-butoxyphenoxy)carbonyl]phenyl-3",5"-diaminobenzoate (BCDA) was synthesized from 4-butoxyphenol, 4-hydroxybenzoic acid and 3,5-dinitrobenzoic acid through four main intermediates, and a series of polyimides were also synthesized. All the intermediates and the final product were characterized by FTIR and 1H-NMR. The key step in synthesis route is selective hydrolyzation of two ester groups in 4-butoxyphenyl-4'-acetoxybenzoate, by adjusting the reaction temperature and the concentration of ammonia, shorteding the reaction time. The properties of the novel polyimides, such as the aggregation structures, glass transition temperature, solubility and the pretilt angles, were carried out.     

The nucleophilic substitution reaction for [18F]fluoride-ion on the series of N6-benzoyl-2",3"-isopropylideneadenosine-5"-sulfonates

The reaction of the nca [¹⁸F]fluoride ion was investigated toward a series of N⁶-benzoyl 2",3"-isopropylidene-adenosine-5"-sulfonates including the methane-(mesylate), p-toluene-(tosylate), p-nitro-benzene-(nosylate)- and 2,2,2-trifluoro-ethane-sulfonate (tresylate) derivatives under usual nucleophilic substitution conditions. In these reactions cyclisation of the title compounds was observed whilst the radiofluorination took place only with low yield. The fluorine-18 uptake was found to be 1.17% for mesylate, 1.46% for tosylate, 0.99% for nosylate and 0.40% for tresylate under the conditions applied.     

新型3-取代-6-(4-氯苯基)-7-(1H-1,2,4-三唑-1-基)-1',2',4'-三唑[3,4-b]-1",3",4"-噻二嗪衍生物的合成及抗菌活性

通过3-取代-4-氨基-5-巯基-1,2,4-三唑(3a～3m)和2-溴-2-(1H–1,2,4-三唑-1-基)-4′-氯代苯乙酮(2)的缩合反应,合成了13个新型3-取代-6-(4-氯苯基)-7-(1H-1,2,4-三唑-1-基)-1',2',4'-三唑[3,4-b]-1",3",4"-噻二嗪衍生物4a～4m.化合物结构经元素分析,1HNMR,IR和MS进行了表征.抗菌试验表明所合成的化合物对细菌表现出中等程度的抑制活性.     

Spectroscopic study on charge transfer molecular complexes of pyrazole derivatives with some pi-electron acceptors

Charge transfer molecular complexes of some pyrazole donors (pyrazole, 4-methylpyrazole, 3-methylpyrazole and 3,5-dimethylpyrazole) with 2,3-dichloro-5,6-dicyano-1,4-p-benzoquinone and tetracyanoethylene as pi-electron acceptors have been studied in CH2Cl2 at 25 degrees C. Spectral characteristics and stability constants of the formed charge transfer (CT) complexes are discussed in terms of the nature of donor and acceptor molecular structure, as well as in relation to solvent polarity. Thermodynamic parameters (deltaH, deltaG and deltaS) associated with CT complex formation are also examined. It was concluded that the formed CT complexes are of n-pi type with 1:1 (D:A) composition.     

Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene and characterization of their copolymer with tunable fluorescence properties

Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene was successfully achieved in boron trifluoride diethyl etherate by direct anodic oxidation of the monomer mixtures. The structure and properties of the copolymers were investigated with ultraviolet–visible, Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, fluorescence spectra, and thermal analysis. The novel copolymers had the advantages of both poly(9,10-dihydrophenanthrene) and poly(3-methylthiophene), such as good electrochemical behavior, good mechanical properties, and high electrical conductivity. Fluorescence spectroscopy studies revealed that the copolymers had good fluorescence properties, and the emitting properties of the copolymer could be parameters by changing the feed ratio of the monomer mixtures during the electrochemical polymerization.     

6′，6″-二吡啶基-2，2′：4′，4″：2″，2′′′-四联吡啶稀土配合物的合成、表征及荧光性质研究(英)

Two series of solid complexes of rare earth nitrates and picrates with the “back-to-back” terpyridine, 6′,6″-bis(2-pyridyl)-2,2′:4′,4″:2″,2′′′-quaterpyridine (L) have been synthesized. These complexes have been characterized by elemental analysis, conductivity measurements, thermal analysis and IR spectroscopy. At the same time, the luminescent properties of the Eu(Ⅲ) and Tb(Ⅲ) complexes were also studied.     

Salpianthus macrodontus Extracts,a Novel Source of Phenolic Compounds with Antibacterial Activity against Potentially Pathogenic Bacteria Isolated from White Shrimp

This study aimed to evaluate the antibacterial activity in vitro of Salpianthus macrodontus and Azadirachta indica extracts against potentially pathogenic bacteria for Pacific white shrimp. Furthermore, the extracts with higher inhibitory activity were analyzed to identify compounds responsible for bacterial inhibition and evaluate their effect on motility and biofilm formation. S. macrodontus and A. indica extracts were prepared using methanol, acetone, and hexane by ultrasound. The minimum inhibitory concentration (MIC) of the extracts was determined against Vibrio parahaemolyticus, V. harveyi, Photobacterium damselae and P. leiognathi. The polyphenol profile of those extracts showing the highest bacterial inhibition were determined. Besides, the bacterial swimming and swarming motility and biofilm formation were determined. The highest inhibitory activity against the four pathogens was found with the acetonic extract of S. macrodontus leaf (MIC of 50 mg/mL for Vibrio spp. and 25 mg/mL for Photobacterium spp.) and the methanol extract of S. macrodontus flower (MIC of 50 mg/mL for all pathogens tested). Both extracts affected the swarming and swimming motility and the biofilm formation of the tested bacteria. The main phenolic compounds related to Vibrio bacteria inhibition were naringin, vanillic acid, and rosmarinic acid, whilst hesperidin, kaempferol pentosyl-rutinoside, and rhamnetin were related to Photobacterium bacteria inhibition.     

Convergent synthesis of near-infrared absorbing, "push-pull", bisthiophene-substituted, zinc(II) phthalocyanines and their application in dye-sensitized solar cells

Zinc(II) phthalocyanine dyes that contain triarylamine-terminated bisthiophene and hexylbisthiophene groups have been synthesized by a convergent approach by using carboxytriiodo-ZnPc as a precursor. Further transformation of the iodo groups by a Pd-catalyzed reaction allowed easy preparation of further extended π-conjugated carboxy-ZnPcs. These dyes have been used as sensitizers in dye-sensitized solar cells, which exhibit a panchromatic response and moderate overall efficiencies.