Self-aggregation of synthetic multi-hydroxylated zinc chlorophylls

A series of zinc 3-hydroxymethyl-13¹-oxo-(bacterio)chlorins possessing additional hydroxy group(s) on the B-ring were synthesized as models of bacteriochlorophylls-c/d/e, self-aggregative light-harvesting pigments of green photosynthetic bacteria. Tertiary and secondary alcoholic moieties on the 7- and/or 8-position(s) did not significantly interact with any other functional groups in their well-ordered self-aggregates. In contrast, the less sterically hindered primary alcoholic hydroxy group at the 7- and 8-substituents slightly caused random orientations of their molecular transition dipole moments in the supramolecule by unfavorable hydrogen bonding, which was competitive with the original 3¹-OH.     

Self-aggregation of synthetic zinc 2-hydroxy-12/13-oxo-porphyrins

Zinc complexes of 2¹-hydroxy-12¹/13¹-oxo-porphyrins were prepared by modifying octaethylporphyrin as models of self-aggregative chlorophylls found in extramembranous antennas of green photosynthetic bacteria. Their visible absorption spectra showed that less hindered interactive groups, such as CH₂OH and CHO in a synthetic zinc porphyrin molecule were necessary for their self-aggregation in non-polar organic solvents. Zinc 2-hydroxymethyl-12-formyl-porphyrin self-aggregated to form larger oligomers with red-shifted broad visible bands than the 2,13-regioisomer, indicating that the linear location of OH, Zn and CO in a molecule is requisite for similar self-aggregation with natural systems.     

Self-aggregation of synthetic zinc oxo-bacteriochlorins bearing substituents characteristic of chlorosomal chlorophylls

We prepared novel zinc 8-ethyl-8-methyl-7-oxo- and 7-ethyl-7-methyl-8-oxo-bacteriochlorins 1 and 2 possessing substituents characteristic of chlorosomal chlorophylls, exclusively observed in extramembraneous light-harvesting antennas of photosynthetic green bacteria. The electronic absorption spectra of monomeric 1 and 2 in THF were obviously different: the Q(y) maximum of the former was 724 and that of the latter was 683 nm. This observed spectral difference was clearly explained by theoretical ZINDO/S calculation of their energetically minimized molecules. The optical properties of monomeric 1/2 were controlled by the electronic effect of the 7/8-oxo groups. Specific spectral changes in the electronic, CD, and FT-IR absorption spectra by dilution of the monomeric THF solutions of 1/2 with a 100/200-fold volume of cyclohexane showed the formation of chlorosomal self-aggregation species constructed by 13-C=O...H-O(3(1))...Zn and pi-pi stacking. Especially, the red-shift values in the Q(y) band of 1/2 by self-aggregation were 2450/1970 cm(-1), indicating that exciton interaction among the composite molecules in the self-aggregation of 1 was stronger than in those of 2. Molecular model calculations for dodecamers of 1/2 based on a parallel chain arrangement gave partially different supramolecular structures; the specific hydrogen-bonding distances in 2-dodecamer were larger than those of 1-dodecamer, while both coordinations gave the same Zn-O distance. These modeling results showed that 1 was more tightly packed in the self-aggregates to give a larger red-shift value in the Q(y) band by self-aggregation than 2. The difference in the supramolecular structures is mainly ascribable to the steric effect of 8/7-dialkyl groups in self-aggregates of 1/2.     

Self-aggregation of synthetic zinc 31-hydroxy-131-oxo-17,18-cis-chlorin in a non-polar organic solvent

Zinc methyl 3¹-demethyl-17,18-cis-bacteriopheophorbide-d was prepared as a model of naturally occurring bacteriochlorophyll-d. From the absorption spectral analysis, the synthetic cis-chlorin self-aggregated in a non-polar organic solvent to give an oligomer possessing red-shifted and broadened peaks, compared to the non-aggregated form. The red-shifted values by self-aggregation were smaller than those observed in the corresponding trans-isomer, indicating that self-aggregates of the cis-isomer took on more disordered supramolecular structures than those of the trans-isomer.     

Self-aggregation of a synthetic zinc chlorophyll derivative possessing a 13-dicyanomethylene group as a light-harvesting antenna model

Zinc methyl 3-hydroxymethyl-13¹-dicyanomethylene-pyropheophorbide-a, one of the bacteriochlorophyll-d analogs, was prepared by modifying chlorophyll-a. The semi-synthetic compound self-aggregated in an aqueous Triton X-100 solution to give large oligomers with red-shifted and broadened electronic absorption bands. The J-aggregates were similar to self-aggregates of bacteriochlorophyll-d molecules in natural light-harvesting antennas of green photosynthetic bacteria. The strongly electron-withdrawing dicyanomethylene group was an alternative functional moiety of the hydrogen-bond accepting 13¹-oxo group which had been necessary for such self-aggregation.     

从炔烃衍生物出发的有机合成方法学

研究了过渡金属催化的炔烃衍生物的异构化反应.从α,β-炔酮、2-炔酸酯和2-炔酸酰胺可以生成相应的(E,E)-共轭双烯酮、双烯酸酯和双烯酸酰胺.首次从2-炔醇异构化为相应的2-烯酮或2-烯醛.这一反应具有简单、高产率和立体选择性的优点.假设反应烯经过连二烯中间体,然后再异构化成产物,这一反应提供了方便而有潜在应用价值的方法以制备天然产物合成时的重要中间体.     

Natural and synthetic pantothenic acid derivatives

A review is given of the latest advances on the chemical synthesis and isolation of natural pantothenic acid, including bioprecursors of CoA. The value of the individual sections of the CoA molecule for the manifestation of coenzyme activity is discussed.Vitaminy Scientific-Industrial Association, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 477–492, July–August, 1988.     

Natural and synthetic pantothenic acid derivatives

A review is given of the latest advances on the chemical synthesis and isolation of natural pantothenic acid, including bioprecursors of CoA. The value of the individual sections of the CoA molecule for the manifestation of coenzyme activity is discussed. Vitaminy Scientific-Industrial Association, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 477–492, July–August, 1988.     

New peroxo derivatives of synthetic montmorillonite structures

New peroxo derivatives of montmorillonite (MT) minerals (cationic clay structures) were prepared. Conditions were found for the synthesis of stable (for 2 years) peroxide varieties of such structures containing high active oxygen percentages (15 wt % O_act or 32 wt % H₂O₂). A scenario for hydrogen peroxide sorption by cationic clays was proposed.     

胺烷基二茂铁衍生物的合成方法

胺烷基二茂铁衍生物由于在有机合成中的特殊用途而受到化学家们的重视，成为二茂铁衍生物中的一个重要研究领域。本文介绍从不同起始原料出发，合成胺烷基二茂铁衍生物的方法。     

Self-aggregation inhibits the photonuclease activity of porphyrins

A series of tentacle porphyrins having four aminoalkyl groups at the periphery was synthesized, and the DNA binding properties were investigated by absorption and circular dichroism (CD) spectroscopic methods. The aminopropyl chain was found to facilitate binding, and bisignate induced CD spectra revealed that the porphyrins are self-stacked on the DNA surface. The photonuclease activity of the tentacle porphyrins was also studied, and the aminopropylporphyrin showed the highest activity. The activity increased in proportion to the porphyrin load, but higher loads resulted in the decrease of activity. This inhibitory step corresponded to aggregation of the porphyrin. Thus, the aggregation was suggested to shield the inner porphyrin from the solvent, the production of active oxygen species being suppressed.     

Biological potential of thiazolidinedione derivatives of synthetic origin

Thiazolidinediones are sulfur containing pentacyclic compounds that are widely found throughout nature in various forms. Thiazolidinedione nucleus is present in numerous biological compounds, e.g., anti-malarial, antimicrobial, anti-mycobacterium, anticonvulsant, antiviral, anticancer, anti-inflammatory, antioxidant, anti-HIV (human immunodeficiency virus) and antitubercular agent. However, owing to the swift development of new molecules containing this nucleus, many research reports have been generated in a brief span of time. Therefore seems to be a requirement to collect recent information in order to understand the current status of the thiazolidinedione nucleus in medicinal chemistry research, focusing in particular on the numerous attempts to synthesize and investigate new structural prototypes with more effective antidiabetic, antimicrobial, antioxidant, anti-inflammatory, anticancer and antitubercular activity.

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Synthesis and antiviral activities of synthetic glutarimide derivatives

A series of novel glutarimide compounds were synthesized and their antiviral activities were evaluated. The compounds displaying the strongest antiviral activities included 5, 6f, 7e and 9 against coxsackievirus B3 (Cox B3), 10 and 6f against influenza virus A (influenza A) and 7a against herpes simplex virus 2 (HSV-2). However, most of the synthetic glutarimides showed comparatively much weaker activity against influenza A, Cox B3 and HSV-2 than the natural glutarimide compounds tested. Based on the results, it seemed likely that a conjugated system at the β-substituted moiety provides stronger antiviral activity.     

Self-aggregation of liquids from biomass in aqueous solution

Aggregation of several chemicals from biomass: furfural derived compounds (furfural, 5-methylfurfural, furfuryl alcohol and tetrahydrofurfuryl alcohol), lactate derived compounds (methyl lactate, ethyl lactate and butyl lactate), acrylate derived compound (methyl acrylate) and levulinate compounds (methyl levulinate, ethyl levulinate and butyl levulinate) in aqueous solution has been characterised at T = 298.15 K through density, ρ, speed of sound, u, and isentropic compressibilities, κ_S, measurements. In addition the standard Gibbs free energies of aggregation have been also calculated. Furthermore, in order to deepen insight the behaviour of these chemicals in aqueous solution, the solubility of these compounds has been measured at T = 298.15 K.     

A novel synthetic strategy for monosubstituted cyclodextrin derivatives

A first solid phase approach to obtain monosubstituted CD conjugates to different labels has been developed. A new solid support has been designed to get a variety of C-6 monofunctionalized CDs (α, β, MeβCD and HPβCD) covalently linked through a phosphodiester bridge to different labels, in highly pure form and under very mild detachment conditions.     

多羟基富勒醇水溶液自聚集行为的研究

利用四丁基氢氧化铵催化法合成了多羟基富勒醇,通过三维荧光光谱结合透射电镜和动态光散射方法,考察了富勒醇水溶液自聚集行为的机理.研究结果表明,当富勒醇溶液的浓度低于4×10-5 mol/L时,富勒醇主要以单体分子形式存在,浓度为4×10-5 ～2×10-4 mol/L时则是以两种分散状态的形式并存,而当浓度高于2×10-4 mol/L时,富勒醇则主要以聚集体的形式存在于水溶液中.     

Electroanalytical study of guanine synthetic derivatives with antiviral activity

Experimental information on the electrochemical behavior of guanine synthetic derivatives (acyclovir, valacyclovir, ganciclovir, and famciclovir) with the strong antiviral activity on presynthesized activated carbosital electrode (CSE) in aqueous solutions of different acidity is obtained. The mechanism of irreversible oxidation of substances containing guanidine group (–NH–C(NH–)=N–) is discussed and the dependences of current and potential of experimental anodic peaks on the potential scan rate, the nature and acidity of supporting electrolyte solution, and also on the concentration of depolarizer and the time of its accumulation on the electrode surface are found. It is shown that all other factors being equal (0.1 М phosphate buffer, рН 6), the position of the observed anodic peak depends substantially on the nature of acyclic substituent at N(9) of imidazole ring in the aminopurine molecule: the susceptibility to oxidation decreases in the series Gua (E_pa = 0.84 V), ACV (E_pa = 1.00 V), VACV (E_pa = 1.04 V), GCV (E_pa = 1.07 V), FCV (E_pa = 1.20 V). It is shown that the electrocatalytic activity and the high absorbability of the activated CSE with respect to substances tested make it possible to reach their lower detection limits (20–40 nM) in multicomponent solutions.     

A general synthetic route to nanofibers of polyaniline derivatives

Nanofibrous mats of a wide variety of polyaniline derivatives can be synthesized without the need for templates or functional dopants by simply introducing an initiator into the reaction mixture of a rapidly mixed reaction between monomer and oxidant.