Tailor-made hexaethylene glycolic ionic liquids as organic catalysts for specific chemical reactions

Hexaethylene glycol substituted imidazolium based ionic liquids (hexaEGILs) were designed and prepared well-tailored to a specific organic reaction using alkali-metal fluorides (MFs) as multifunctional organic catalysts. These hexaEGIL catalysts could significantly enhance the reactivity of MF, even KF. Furthermore, the hexaEGIL systems showed tremendous efficiency in the nucleophilic fluorination of base-sensitive substrates.     

Technology credit rating system for funding SMEs

Technology evaluation has played a crucial role in selecting and supporting companies with innovative technology. Previous studies have focused on developing technology evaluation methods such as scorecard. However, technology credit rating is rarely applied, despite its convenient usage for technology financing. In this paper, we propose a technology credit rating system, called cross matrix, based on empirical data obtained from the technology scoring model and examine their properties. The proposed rating system is expected to provide valuable information for effective management of the technology credit fund.     

Effect of n-alkyl and sulfonyl groups on the wetting properties of comblike poly(oxyethylene)s and stick-slip behavior

The influence of side chain length and sulfonyl moiety on the molecular structures and wettability behavior of poly(oxyethylene)s with alkyl sulfonyl side chains (CH(3)-nSE, n = 1, 2, 3, 4, 5, 6, 8, 10), where n is the number of the carbon atom in the n-alkyl side group, was investigated. CH(3)-nSEs having shorter side chains (n < 5) do not have ordered structures, and their surfaces were found to be more polar than those of CH(3)-nSEs having longer side chains (n ≥ 5). The CH(3)-nSEs having longer side chains show double-layered lamellar structures (n ≥ 5) with well-aligned side chains and low surface energies in the range 21.2-25.8 mN/m. Interestingly, stick-slip behavior was observed only on the surfaces of CH(3)-3SE and CH(3)-4SE when water was used as the test liquid. The surface deformation at the three-phase line was generated from interactions between water and sulfonyl groups, and the optimum side chain lengths were believed to cause the stick-slip behavior.     

Metal ion coordination with an asymmetric fan-shaped dendrimer at the air-water interface

Metal coordination to monolayers of 4-{10-[4-(3,5-bis-benzyloxy)-phenyl]-anthracen-9-yl}-benzoic acid ([G1-An]-CO(2)H, G1) and 4-(10-{4-[3,5-bis-(3,5-bis-benzyloxy)-benzyloxy]-phenyl}-anthracen-9-yl)-benzoic acid ([G2-An]-CO(2)H, G2) at the air-water interface and to Langmuir-Blodgett (LB) films was investigated using surface pressure-area isotherms, ultraviolet-visible (UV-vis) spectroscopy, atomic force microscopy (AFM), and X-ray reflectivity (XRR). Surface pressure-area isotherms show that G1 and G2 have different limiting areas according to the type of subphase. The limiting area of G1 and G2 increased more with Al(3+) than with Eu(3+) in the subphase. This result indicates that the hydrophilic core group is anchored to ions in the water via bidentate chelates with the carboxylate oxygen atoms of G1 and G2. Circular domains and aggregates were observed for the LB film. The different behavior of Eu(3+) and Al(3+) complexes is originated from the intrinsic nature of the ion, i.e., coordination number.     

An efficient and chemoselective deprotection of tert-butyldimethylsilyl (TBDMS) ethers using tailor-made ionic liquid

Phenolic tert-butyldimethylsilyl (TBDMS) ethers can be deprotected to yield phenols in excellent yield using tailor-made ionic liquid [dihexaEGim][OMs] (dihexaEGim = dihexaethylene glycolic imidazolium salt) as an organic catalyst with alkali-metal fluoride in tert-amyl alcohol. On the contrary, all TBDMS protecting groups can be cleaved cleanly from the bis-TBDMS ether using the same reaction in CH₃CN solvent instead of tert-alcohol at 100 °C. This [dihexaEGim][OMs]/tert-amyl alcohol media system allows the highly selective phenolic deprotection reaction of various bis-TBDMS ethers containing both phenolic and aliphatic TBDMS ethers to provide the corresponding phenols in high yield.     

Total synthesis and structure confirmation of elatenyne: success of computational methods for NMR prediction with highly flexible diastereomers

Elatenyne is a small dibrominated natural product first isolated from Laurencia elata. The structure of elatenyne was originally assigned as a pyrano[3,2-b]pyran on the basis of NMR methods. Total synthesis of the originally proposed pyrano[3,2-b]pyran structure of elatenyne led to the gross structure of the natural product being reassigned as a 2,2'-bifuranyl. The full stereostructure of this highly flexible small molecule was subsequently predicted by Boltzmann-weighted DFT calculations of (13)C NMR chemical shifts for all 32 potential diastereomers, with the predicted structure being in accord with the proposed biogenesis outlined below. Herein we report two complementary total syntheses of elatenyne, which confirm the computer-predicted stereostructure. Additionally, the total syntheses of (E)-elatenyne and a related 2,2'-bifuranyl, laurendecumenyne B, are reported. This work has not only allowed the full structure determination of all of these natural products but also provides excellent supporting evidence for their proposed biogenesis. The total synthesis of elatenyne demonstrates that DFT calculations of (13)C NMR chemical shifts coupled with biosynthetic postulates, comprise a very useful method for distinguishing among large numbers of highly flexible, closely related molecules.     

Surface morphology of GaN nanorods grown by catalyst-free hydride vapor phase epitaxy

GaN nanorods were grown on c-plane sapphire substrates by using catalyst-free hydride vapor phase epitaxy (HVPE). The effects of substrate temperature, Ga boat temperature, and Ga pretreatment on the surface morphology of GaN nanorods were investigated. From the dependence of a radial and axial growth rate on the substrate temperature, the kinetically limited process was found to be a rate determining step in the growth of GaN nanorods in HVPE. In addition, the activation energy of the growth along the both axial and radial directions were estimated. The dependence of a Ga boat temperature and the Ga pretreatment effect revealed that the density of nanorods were dependent on the flux of Ga species on the substrate.     

Explicit bounds of polynomial coefficients and counting points on Picard curves over finite fields

In this paper, we describe an algorithm for computing the order of the Jacobian varieties of Picard curves over finite fields. This is an extension of the algorithm of Matsuo, Chao and Tsujii (MCT) [K. Matsuo, J. Chao, S. Tsujii, An improved baby step algorithm for point counting of hyperelliptic curves over finite fields, in: LNCS vol. 2369, Springer-Verlag, 2005, pp. 461–474] for hyperelliptic curves. We study the characteristic polynomials and the Jacobian varieties of algebraic curves of genus three over finite fields. Based on this, we investigate the explicit computable bounds for coefficients of the characteristic polynomial and improve a part of the baby-step giant-step of the counting points algorithm. Usefulness of the proposed method is illustrated and verified by the simple examples.