Control of chain ends of polyesters in polycondensation of AA and BB monomers by use of solid‐phase reagent

For selective synthesis of linear polyester having a functional group at one end, polycondensation between 1,4‐butanediol ( 1a ) and sebacoyl chloride ( 2a ) and between 1,12‐dodecanediol ( 1b ) and isophthaloyl chloride ( 2b ) was conducted in the presence of oxime resin or oxime silica gel, followed by cleavage of the formed polyester from the solid‐phase support with aniline. Matrix‐assisted laser desorption ionization time‐of‐flight mass spectra and ¹H NMR spectra of the cleaved polyester showed that the products contained not only polyester with anilide at one end ( poly 1 ), but also polyester with anilides at both ends ( poly 2 ). The product ratio of poly 1 to poly 2 ( poly 1 / poly 2 ) was dependent on monomers, monomer concentration, feed ratio of monomer to oxime moiety in the support, oxime content in the support, reaction solvent, and the nature of the support. Polyester with a high poly 1 / poly 2 ratio of 81/21 and moderate molecular weight (M_n = 1430 g/mol) was obtained by polycondensation of 1b and 2b in the presence of oxime silica gel in dichloromethane. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1379–1386     

Synthesis and photophysical properties of azuleno[1′,2′:4,5]pyrrolo[2,1-b]quinazoline-6,14-diones: Azulene analogs of tryptanthrin

Azulene analog of tryptanthrin, azuleno[1′,2′:4,5]pyrrolo[2,1-b]quinazoline-6,14-dione, was successfully prepared by the condensation reaction of azuleno[2,1-b]pyrrole-2,3-dione with isatoic anhydride in the presence of sodium hydride or diisopropylethylamine (DIPEA). Its 2-halo derivatives were also obtained in high yields by the condensation reaction with 5-haloisatoic anhydrides in the presence of DIPEA. Reactivity toward electrophilic reagents was revealed by halogenation with N-bromosuccinimide (NBS) or N-iodosuccinimide (NIS) to afford 12-halo derivatives in high yields. Among the halo derivatives, 2-iodo and 12-iodo derivatives were reactive enough to afford phenylethynyl derivatives under Pd-catalyzed Sonogashira cross-coupling conditions. Within the phenylethynyl derivatives, only 12-phenylethynyl derivative was transformed into its 1,1,4,4-tetracyanobutadiene (TCBD) derivative by the reaction with TCNE. Amphoteric redox properties of the novel azulene analogs of tryptanthrin were characterized by spectroscopic and voltammetric analyses.     

Properties and structure of glasses in the system AsS

In obtaining the glass, at first, the raw materials were mixed up and melted by using porcelain crucible, but in this case it was found by infra-red absorption method that the glass contains some oxygen impurities. Then a range of glasses was prepared by melting elementary pure As and S in definite proportions in a sealed vacuum tube. The infra-red absorption, molecular volume, molecular refraction, hardness, thermal expansion and viscosity of sample glasses with various compositions were investigated and, additionally, solubility of these glasses into CS₂ was measured. The structure of glasses in the system AsS was studied by X-ray diffraction and a structural model was set up. From the measurements the following conclusions were made. The structure of As₂S₃ glass is a distorted form of the crystalline orpiment structure. With increasing S content above As₂S₃, S is likely to exist in the chain-like form, but when the S content is greater than that in As₂S_8–10, both chain-like and ring type forms co-exist. With decreasing S content below As₂S₃, S between As and As is eliminated and AsAs bonds are formed. Consequently a deformation of layer occurs and an expansion of the layer distance was observed.     

Formal total synthesis of fostriecin via 1,4-asymmetric induction using cobalt-alkyne complex

The synthesis of a protected dephosphofostriecin, and thereby a formal synthesis of fostriecin, has been accomplished. Two of the four chiral centers are controlled by an external chiral auxiliary and the other two are synthesized stereoselectively, one by a novel 1,4-asymmetric induction using cobalt-alkyne complex, and the other by 1,3-asymmetric induction.     

Synthesis of chitosan resin possessing a phenylarsonic acid moiety for collection/concentration of uranium and its determination by ICP-AES

A chitosan resin possessing a phenylarsonic acid moiety (phenylarsonic acid type chitosan resin) was developed for the collection and concentration of trace uranium prior to inductively coupled plasma (ICP) atomic emission spectrometry (AES) measurement. The adsorption behavior of 52 elements was systematically examined by packing it in a minicolumn and measuring the elements in the effluent by ICP mass spectrometry. The resin could adsorb several cationic species by a chelating mechanism, and several oxo acids, such as Ti(IV), V(V), Mo(VI), and W(VI), by an anion-exchange mechanism and/or a chelating mechanism. Especially, U(VI) could be adsorbed almost 100% over a wide pH region from pH 4 to 8. Uranium adsorbed was easily eluted with 1 M nitric acid (10 mL), and the 25-fold preconcentration of uranium was achieved by using a proposed column procedure, which could be applied to the determination of trace uranium in seawater by ICP-AES. The limit of detection was 0.1 ng mL⁻¹ for measurement by ICP-AES coupled with 25-fold column preconcentration.     

Size dependence of transition temperature in polymer nanowires

We studied the effect of changing temperature on the mechanical properties of nanosized poly(methyl methacrylate) wires fabricated by two-photon fabrication. At around room temperature, the nanowires showed a transition temperature where the shear modulus suddenly changed. This transition temperature was observed to decrease more than 40 K by decreasing the radius of the nanowires from 450 to 150 nm. This size is several times larger in nanowires than reported values of polymer thin film thickness showing a depression of the glass transition temperature.     

Novel formation of iodobenzene derivatives from 1-(methylthio)-3-tosylhexa-1,3-dien-5-ynes via iodine-induced intramolecular cyclization

The reaction of (1E,3E)-1-(methylthio)-3-tosylhexa-1,3-dien-5-ynes (3) with iodine to form iodine-substituted benzenes (4) is reported. The reaction of 3 with iodine proceeded very slowly, but UV irradiation accelerates the reaction to give 4 in high-to-excellent yields. Irradiation induces the cis-trans isomerization of the C1-C2 double bond, leading to the (1Z,3E)-geometric isomer (3'), which easily reacts with iodine to afford 4. This reaction is applicable to 3-(methoxycarbonyl)-1-(methylthio)-6-phenylhexa-1,3-dien-5-yne (11), which is synthesized as a geometric mixture. Interestingly, this mixture can be used as the starting material. Irradiation of the mixture (the geometric isomer ratio = 50:28:5:17) with iodine resulted in the formation of methyl 3-iodo-4-phenylbenzoate (12) in 80% yield.     

Preparation of pH-sensitive liposomes retaining SOD mimic and their anticancer effect

We prepared an anticancer drug based on a pH-sensitive liposome retaining Fe-porphyrin as an SOD mimic. The liposomes contained cationic/anionic lipid combinations and were composed of Fe-porphyrin, 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine, dimethylditetradecylammonium bromide, sodium oleate, and Tween-80. The Fe-porphyrin was released from the liposome at low pH, and the cytotoxicity for cancer cells by the liposome depended on the acidic environments of the endosomes in the cells. Furthermore, although the liposome exhibited an excellent anticancer effect on a gastric cancer cell line, the SOD activity of Fe-porphyrin was shown to have a significant influence on the cytotoxicity toward cancer cells. These findings suggest that the pH-sensitive liposome retaining the Fe-porphyrin as an SOD mimic promises to be a novel anticancer drug for endosomal escape.     

Reversible mechanochromic luminescence of [(C6F5Au)2(mu-1,4-diisocyanobenzene)

Reversible mechanochromic luminescence of [(C6F5Au)2(mu-1,4-diisocyanobenzene)] is reported. Grinding of the complex induced a photoluminescent color change, which was restored by exposure to a solvent. This cycle was repeated 20 times with no color degradation in the emissions. Their optical properties, X-ray crystallographic analysis, IR, and XRD measurements strongly suggested that the change in the molecular arrangement is responsible for this mechanochromic property. Intermolecular aurophilic bondings presumably play a key role in the altered emission.     

Synthesis, structures, and properties of group 9- and group 10-group 6 heterodinuclear nitrosyl complexes

The reaction of the group 9 bis(hydrosulfido) complexes [Cp*M(SH)2(PMe3)] (M=Rh, Ir; Cp*=eta(5)-C 5Me5) with the group 6 nitrosyl complexes [Cp*M'Cl2(NO)] (M'=Mo, W) in the presence of NEt3 affords a series of bis(sulfido)-bridged early-late heterobimetallic (ELHB) complexes [Cp*M(PMe3)(mu-S)2M'(NO)Cp*] (2a, M=Rh, M'=Mo; 2b, M=Rh, M'=W; 3a, M=Ir, M'=Mo; 3b, M=Ir, M'=W). Similar reactions of the group 10 bis(hydrosulfido) complexes [M(SH)2(dppe)] (M=Pd, Pt; dppe=Ph 2P(CH2) 2PPh2), [Pt(SH)2(dppp)] (dppp=Ph2P(CH2) 3PPh2), and [M(SH)2(dpmb)] (dpmb=o-C6H4(CH2PPh2)2) give the group 10-group 6 ELHB complexes [(dppe)M(mu-S)2M'(NO)Cp*] (M=Pd, Pt; M'=Mo, W), [(dppp)Pt(mu-S)2M'(NO)Cp*] (6a, M'=Mo; 6b, M'=W), and [(dpmb)M(mu-S)2M'(NO)Cp*] (M=Pd, Pt; M'=Mo, W), respectively. Cyclic voltammetric measurements reveal that these ELHB complexes undergo reversible one-electron oxidation at the group 6 metal center, which is consistent with isolation of the single-electron oxidation products [Cp*M(PMe3)(mu-S)2M'(NO)Cp*][PF6] (M=Rh, Ir; M'=Mo, W). Upon treatment of 2b and 3b with ROTf (R=Me, Et; OTf=OSO 2CF 3), the O atom of the terminal nitrosyl ligand is readily alkylated to form the alkoxyimido complexes such as [Cp*Rh(PMe3)(mu-S)2W(NOMe)Cp*][OTf]. In contrast, methylation of the Rh-, Ir-, and Pt-Mo complexes 2a, 3a, and 6a results in S-methylation, giving the methanethiolato complexes [Cp*M(PMe3)(mu-SMe)(mu-S)Mo(NO)Cp*][BPh 4] (M=Rh, Ir) and [(dppp)Pt(mu-SMe)(mu-S)Mo(NO)Cp*][OTf], respectively. The Pt-W complex 6b undergoes either S- or O-methylation to form a mixture of [(dppp)Pt(mu-SMe)(mu-S)W(NO)Cp*][OTf] and [(dppp)Pt(mu-S) 2W(NOMe)Cp*][OTf]. These observations indicate that O-alkylation and one-electron oxidation of the dinuclear nitrosyl complexes are facilitated by a common effect, i.e., donation of electrons from the group 9 or 10 metal center, where the group 9 metals behave as the more effective electron donor.