An Efficient Steric Controlled Photo-Fries Rearrangement in the Naphthalene Series

For the work on the synthesis of 2-acyl-5-methoxynaphthoquinones as tricyclic analogues of daunomycinone¹, we wanted to develop an efficient regioselective synthesis of 5-methoxy-2-acyl-1-naphthols without using Lewis acids. This requirement precluded the use of the thermal Fries but not the photo-Fries rearrangement. Although the mechanistic aspects of the photo reaction have received much study², the reaction has been little used preparatively³ because it usually gives poor yields of hydroxy ketones even when only one product is possible.     

CROSS-LINKING OF AROMATIC POLY（THIOETHER）S

A novel cross-linking process using two high molecular weight aromatic poly(thioether)s,which were synthesized by the reactions of 4,4′-thiobisbenzenethiol with 4,4′-difluorobenzophenone and 4,4′-difluorodiphenylsulfone,respectively, and commercially available lower molecular weight poly(p-phenylene sulfide)was investigated.These reactions were carried out in bulk by the addition of silver tetrafluroborate andα,α′-dibromo-p-xylene at 190℃over a period of 45 min. Furthermore,the same procedure could be modified to cross-link compression-molded films of these three polymers.The thermal and solubility behaviors of these polymers before and after cross-linking reactions,are presented.     

Studies on coordination chemistry of a nitrogen–sulfur donor ligand with lighter and heavier metal ions and biological activities of its complexes

Complexes of S-benzyldithiocarbazate (SBDTC) with lighter and heavier metals, viz., Cr^III, Fe^III, Sb^III, Zr^IV, Th^IV and U^VI have been prepared and characterized by elemental analyses, conductivity measurements, and spectral studies. The complexes: [Cr(SBDTCA)₃],^** [Fe(SBDTCA)₃], [Sb(SBDTCA)₃], [Sb(SBDTCA)₂Cl · H₂O], [Zr(O)(SBDTCA)₂ · H₂O], [Th(SBDTCA)(NO₃)₃ · H₂O)], and [U(O)₂(SBDTCA)₂] were all prepared in alkaline media. They were all hexa-coordinated with bidentate, uninegative chelation of the ligand. [Fe(SBDTCA)₃], [Sb(SBDTCA)₃] and [Sb(SBDTCA)₂Cl · H₂O] were strongly effective against bacteria giving clear inhibition zones with Pseudomonas aeruginosa and Bacillus cereus. The compounds showed poor antifungal activity. The antimony complexes were strongly cytotoxic against leukemic cells with CD₅₀ values of 3.2–6.7 g cm^–3 as compared to the CD₅₀ value of 14.5 g cm^–3 of the free SbCl₃ molecule.     

直接键连原子间的NMR偶合常数的自然杂化轨道研究V.~(13)C-~(13)C和~(13)C-~(31)P核自旋偶合常数~1J_(CC)和~1J_(CP)

在前文工作的基础上，结合ＭＮＤＯ／ＥＨＭＯ分子轨道方法和自然杂化轨道方法，具体计算了ＣＣ键和ＣＰ键的核自旋偶合常数．计算结果表明，１ＪＣＣ和１ＪＣＰ主要由成键原子的轨道杂化作用和键极性这两种结构因素所决定．为从简单价键理论角度解释和计算１ＪＣＣ和１ＪＣＰ值提供了简便直观的方法．     

Growth, new growth, and amplification of carbon nanotubes as a function of catalyst composition

Carbon nanotubes (CNTs) have been grown using Fe, Co, Ni, and Co/Fe spin-on-catalyst (SOC) systems, involving the metal salt dispersed with a spin-on-glass precursor. During initial growth runs (CH4/H2/900 degrees C), the CNT yield followed the order Co-SOC > Fe-SOC > Ni-SOC. The Fe catalysts produced the longest nanotubes at the expense of a larger average CNT diameter and broader diameter distribution than the Co-SOC system. A series of Co/Fe-SOCs were prepared where as the atomic percentage of Co is increased nucleation of CNT increases but the CNT length decreases. The linear relationship between the diameter and length of CNTs grown from the Co/Fe-SOC suggests that slow growth is beneficial with respect to control over CNT diameter. After initial CNT growth, the original samples were subjected to additional growth runs. Four individual reactions were observed in the Fe-SOC and binary Co/Fe-SOC: regrowth (amplification), double growth (a second CNT growing from a previously active catalyst), CNT etching, and nucleation from initially inactive catalysts (new growth). CNT etching was observed for the mixed catalyst systems (Co/Fe-SOC) but not for either Fe-SOC or Co-SOC. During the regrowth experiments, CNTs were observed that were not present after the initial growth run (and were not as a result of amplification or double growth). Thus, catalysts, which were initially inactive toward nucleation of CNTs in the original growth run, are capable of becoming activated when placed back into the furnace and submitted to regrowth under identical conditions.     

Quenching of tryptophan fluorescence in various proteins by a series of small nickel complexes

A series of twelve anionic, cationic, and neutral nickel(II) complexes have been synthesized and characterized. The interaction of these complexes with bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lyso), and tryptophan (Trp) has been studied using steady-state fluorescence spectroscopy. Dynamic and static quenching constants have been calculated, and the role played in quenching by the ligand and complex charge investigated. The nickel complexes showed selectivity towards the different proteins based on the environment surrounding the Trp residue(s). Only small neutral complexes with hydrophobic ligands effectively quenched protein fluorescence via static quenching, with association constants ranging from 10(2) M(-1) (free Trp) to 10(10) M(-1) (lysozyme), indicating a spontaneous and thermodynamically favorable interaction. The number of binding sites, on average, was determined to be one in BSA, HSA and free Trp, and two in lysozyme.     

Coordination chemistry and biological activity of two tridentate ONS and NNS Schiff bases derived from S-benzyldithiocarbazate

Two tridentate Schiff bases having ONS and NNS donor sequences were prepared by condensing S-benzyldithiocarbazate (NH₂NHCSSCH₂Ph) (SBDTC) with pyridine-2-carboxaldehyde and salicylaldehyde, respectively. Complexes of these ligands with Ni^II, Zn^II, Cr^III, Co^II, Cu^II, and Sn^II were studied and characterized by elemental analyses and various physico-chemical techniques. Ni^II, Cu^II, Zn^II and Sn^II complexes were four-coordinate while the Cr^III, Sr^III and Co^III complexes were six-coordinate. The ONS Schiff base was moderately active against leukemia, while its zinc, antimony and cobalt complexes were strongly active against leukemic cells with DC₅₀ = 0.35–5.00.