The present review is focused on the site-selective deposition of inorganic thin films on self-assembled monolayer (SAM) templates. SAMs were used to modify the substrate surface with chemical functional groups. The patterned SAM substrate was prepared by exposing the SAM substrate to UV light through photomasks for photocleavage. The patterned SAM was used as the templates for deposition of ceramic thin films in aqueous solutions. The preparation and characterization methods of SAMs, and the preparation of the patterned SAM templates are explained. Solution chemistry for the deposition of ceramic oxides and the physics and chemistry of interfaces are described. Experimental examples are given to explain how these aspects influence the formation of films and their properties. Various examples of site-selective deposition of ceramic oxides on SAM templates are explained with classification into three categories: patterning by site-selective attachment of homogeneously nucleated particles, patterning by surface-selective heterogeneous nucleation and growth, and patterning by catalyst-induced heterogeneous nucleation. We also describe pattern-deposition on flexible substrates and future views to improve the pattern resolution.
Novel processes of the site-selective deposition of ceramic oxide thin films on the patterned self-assembled monolayer (SAM) template are investigated. Nucleation and growth of the ceramics in aqueous solutions on the functionalized surfaces are controlled by using SAMs.
This account reviews the chemistry of “boryl anion.” Boryl anions can be classified with their metallic counterpart, such as Li, Mg, Cu, and Zn in a similar manner to the classification of carbanions. The early attempts to generate boryl anions by reductive dehalogenation of haloboranes with alkali metal or photolysis of tetraphenylborate compounds had no modern spectroscopic identification of the reactive “boryl anion.” Recent developments of base-stabilized boryl anion, base–BH2−M+ (base = NEt3 or PCy3, M=K or Li), and generation of borylcopper species, “pinBCuL,” have opened a new area of organoboron chemistry. Recently, we have synthesized a lithium salt of boryl anion, boryllithium, which reacted with electrophiles as a boron nucleophile. Based on the high reactivity of boryllithium, transmetallation to other metals enables synthesis of a series of borylmetals, such as borylmagnesium, borylcopper, and borylzinc species. All of these compounds were isolated and structurally characterized to have an sp2 boron atom. Reactivity with organic electrophiles could confirm that they behaved as boron nucleophiles.
Chemistry of “boryl anion,” which has nucleophilicity toward electrophiles, has been reviewed. Boryl anion having a lithium cation was transferred to other metal cations to form the corresponding boryl anion family.
A rhenium complex, [ReBr(CO)3(thf)]2, catalyzes the insertion of α,β-unsaturated carbonyl compounds into a C–H bond of aromatic compounds having nitrogen-containing directing groups. In this reaction, Re2(CO)10 can also be used as a catalyst. When imines are employed as the aromatic substrates, sequential cyclization proceeds and indene derivatives are obtained in good to excellent yields. This reactivity is in contrast to those of ruthenium and rhodium complexes, which are usually used as catalysts in the insertion reactions of unsaturated molecules into a C–H bond. Investigations on the reaction mechanism indicate that the rhenium catalyst promotes C–H bond activation of aromatic compounds, the insertion of α,β-unsaturated carbonyl compounds into a Re–C bond, and intramolecular nucleophilic cyclization followed by reductive elimination and the elimination of an amine.
A rhenium complex, [ReBr(CO)3(thf)]2, catalyzes the insertion of α,β-unsaturated carbonyl compounds into a C–H bond of aromatic compounds. When imines are employed as the aromatic substrates, sequential cyclization proceeds, and indene derivatives are obtained. The reaction mechanisms are also investigated.
To investigate the effect of hydration and self-association on the reaction mechanism of proton transfer in methimazole (3-methyl-1H-imidazole-2(3H)-thione) and 1H-imidazole-2(3H)-thione, quantum chemical calculations were performed at the B3LYP/6-311++G(2d,2p) level of theory. The binding energies of complexes formed in self-assisted reaction are greater than H2O-assisted reactions. The results show that the thione complexes are more stable than corresponding thiols. The energy barrier for direct proton-transfer tautomerization reaction is significantly greater than self-assisted and H2O-assisted transfer tautomerization. Direct transition is more difficult than the water-assisted and self-assisted processes both thermodynamically and dynamically. The small negative value of H(r) obtained by AIM analysis at the B3LYP/6-311++G(2d,2p) level reveals some contribution of sharing interaction (partially covalent) to the S···HN bond. AIM data also reveal the partially covalent nature of S···H5 interaction and electrostatic nature of O···H6 interaction in the hydrated complexes. In the present complexes, results obtained by NBO analysis show that there is an increase in the σ* population of the N–H bond in A(C) and that of O–H bond in W upon dimerization.
The “cis effect” is a phenomenon in which the cis isomer is more stable than the corresponding trans isomer or almost the same stability in some molecules with double bonds. In order to clarify the predominant factor of this cis effect in the 1,2-dihaloethenes (XHC=CHX; 1: X=F, 2: Cl, and 3: Br), the energetic amount of electron delocalizations and steric exchange repulsions were theoretically estimated using the natural bond orbital (NBO) theory at MP2/6-311++G(3df,3pd) level. Two delocalization mechanisms, periplanar hyperconjugations (synperiplanar and antiperiplanar effects) and halogen lone pair delocalizations into the C=C bond antibonding orbitals (LP effect), were found as the cis stabilizing forces, in which the total amount of LP effect was greater than those of periplanar effects, the dominant factor of the cis effect. Moreover, the origin of the cis preference of the LP effect was clearly elucidated with the application of orbital phase theory, i.e., the cyclic orbital interaction was continuous only in the cis isomers of 1–3. The total steric exchange repulsion between two isomers were all trans stabilizing and their energetic gains were 1.26, 16.48, and 23.22 kJ mol−1 for 1, 2, and 3, respectively. These steric forces obviously counteract against cis preferable delocalization mechanisms, especially in compounds with larger halogen atoms, but their amounts are apparently less than those of electron delocalizations (29.82, 40.00, and 34.46 kJ mol−1 for 1, 2, and 3, respectively). Therefore, electron delocalization, not exchange repulsion, has the largest responsibility for the relative energies of 1,2-dihaloethene systems. The importance of this work is the quantitative elucidation of the dominance of delocalization mechanisms over steric effects on the electronic and energetic view of a simple molecular structure.
Combinatorial enumeration of alkanes as three-dimensional structures has been investigated, where the degrees of internal branching have been taken into consideration by introducing branching indicators (BIs, i.e., q, t, s, and p). After generating functions for counting preformed alkyl moieties (PAMs) were calculated by following Fujita’s proligand method (S. Fujita, Theor. Chem. Acc.2005, 113, 73; 2005, 113, 80; 2006, 115, 37), they have been introduced into functional equations for counting alkanes so as to give the corresponding generating functions, where such alkanes of carbon content k have been categorized into four cases in terms of centroidal/bicentroidal nature and achirality/chirality. Thereby, the generating functions of the respective cases have given the numbers of alkanes, where each number appears as the coefficient of the term called a branching monomial (BM) , when such an alkane contains nq quaternary, nt tertiary, ns secondary, and nq quaternary carbons (k=nq+nt+ns+np). The results of the enumeration have been verified by drawing alkanes of several representative cases, where a mode of divergence, i.e., [nq, nt, ns, and np], has been used for the purpose of qualitative discussions. Previous approaches without considering BIs have been derived by disregarding the effect of internal branching. Moreover, the functional equations for counting 3D structures have been systematically reduced into those for counting graphs, where graph-reduction conditions have been formulated to rationalize the reduction processes. Thereby, Pólya’s theorem for counting graphs has been shown to be a special case of Fujita’s proligand method for counting 3D structures. As a result, difference between stereoisomers (3D structures) and constitutional isomers (graphs) has been discussed by the common criterion due to BMs (or modes of divergence), which provides more detailed enumerations than previous enumerations due to carbon contents (or constitutions).
Dinuclear palladium(II) complex with 1,4,8,11-tetrakis(2-p-toluenesulfonamidoethyl)-1,4,8,11-tetraazacyclotetradecane (H4tstaec), [Pd2(tstaec)], was synthesized and characterized by elemental analysis and IR and UV–vis spectroscopies. The crystal structures of H4tstaec and [Pd2(tstaec)] were determined by single-crystal X-ray diffraction method. In the former ligand, the cyclam ring moiety takes a trans IV conformation with the tosyl arms pointing away from each other, whereas each palladium atom is bound by two nitrogen atoms of the cyclam moiety and two nitrogen atoms of the tosyl arms with Pd···Pd distance of 5.617(1) Å intervening the trans IV cyclam ring in the latter complex. DFT calculations were performed based on these crystal structures.
A series of palladium(II) complexes containing bis[(4-isonicotinoyloxy)phenyl]sulfide (L), [PdII(L)(tmen)]2X4 (tmen = N,N,N',N'-tetramethylethane-1,2-diamine; X=NO3 and ClO4) were prepared and characterized. Reaction of [Pd(tmen)](NO3)2 with L in a mixture of water and acetone affords microspheres whereas reaction of [Pd(tmen)](ClO4)2 with L produces microbelts. The solubility of the products is a significant factor for the formation of morphology. The spherical sizes can be controlled by the evaporation rate of solvents. An array of ≈300 nm and ≈4 μm bimodal spheres was carried out via sonication.
An orange-yellow vanadomolybdate complex was prepared by heating a 100 mM MoVI–20 mM VV–0.45 M HCl–20% (v/v) CH3CN system at 70 °C for 24 h, being isolated as the tetrapropylammonium (Pr4N+) salt. The Pr4N+ salt crystallized in the orthorhombic space group P21212; the lattice constants were a=18.417(4), b=20.869(5), c=15.280(3) Å, V=5873(2) Å3, and Z=2. The crystallographic study revealed that the structure consists of an α-Wells–Dawson-type [V2Mo18O62]6− anion, in which vanadates serve as the central tetrahedra. The α-[V2Mo18O62]6− complex underwent a two-step one-electron reduction in CH3CN, and the presence of acid caused the one-electron waves to be converted into three two-electron waves. The formation conditions were elucidated by 51V NMR measurements.
Reaction of guaiazulene with 1,2-bis[4-(dimethylamino)phenyl]-1,2-ethanediol in methanol in the presence of hydrochloric acid at 60 °C for 3 h gives 1,1-bis[4-(dimethylamino)phenyl]-2-(3-guaiazulenyl)ethylene, in 81% yield, via pinacol rearrangement and further Wittig reaction of 3-formylguaiazulene with [4-(dimethylamino)benzyl]triphenylphosphonium bromide in ethanol containing NaOEt at 25 °C for 24 h under argon affords (E)-2-[4-(dimethylamino)phenyl]-1-(3-guaiazulenyl)ethylene in 12% yield. Crystal structures as well as spectroscopic and electrochemical properties of the products, with a view to comparative study, are reported. Moreover, reactions of the products with 2 equiv of tetracyanoethylene (TCNE) in benzene at 25 °C for 24 h under argon give 1,1,2,2,11,11,12,12-octacyano-3,3-bis[4-(dimethylamino)phenyl]-8-isopropyl-5,10-dimethyl-1,2,3,6,9,10a-hexahydro-6,9-ethanobenz[a]azulene and 1,1,2,2,11,11,12,12-octacyano-3-[4-(dimethylamino)phenyl]-8-isopropyl-5,10-dimethyl-1,2,3,6,9,10a-hexahydro-6,9-ethanobenz[a]azulene in 74 and 41% yields. A plausible reaction pathway for the formation of the unique products, possessing interesting structures, is submitted.
Aptamers are an attractive candidate for a molecular-targeted drug since they can show ability to precisely recognize proteins with a large affinity similar to antibodies. A drawback of aptamers is that they can be easily degraded under biological conditions by DNase (or RNase). In this study, we attached poly(dA) tail to the 3′ end of thrombin DNA aptamer and found that its survival time in human plasma was prolonged by about threefold compared to the original aptamers (i.e., without the tail). We found that the attachment of a poly(dA) tail at the 3′ end caused an increase of the clotting inhibitory activity. A preliminary in vivo assay using BALB/c mice confirmed a considerably elongated clotting time for the tailed aptamer. When the poly(dA) tail was attached to three other DNA aptamers, DNase resistance was increased, indicating that the present finding can be universally applied to increase stability of DNA aptamers.
Intramolecular charge-transfer compounds composed of 1-alkyl-3,3-dimethyl-2-methyleneindoline (In, donor, n = alkyl chain length; 1 or 6) and 7,8,8-tricyanoquinodimethane (=2-(4′-cyanomethylene-2′,5′-cyclohexadienylidene)malononitrile, 3CNQ, acceptor) moieties afforded charge-transfer complexes with 7,7,8,8-tetracyanoquinodimethane (TCNQ): (I1–3CNQ)2(TCNQ) and (I6–3CNQ)(TCNQ). (I1–3CNQ)2(TCNQ) included two kinds of I1–3CNQ molecules of different molecular conformations. (I1–3CNQ)2(TCNQ) and (I6–3CNQ)(TCNQ) were constructed from one-dimensional columns of 3CNQ···TCNQ···3CNQ triads and 3CNQ···TCNQ dyads, respectively. These complexes exhibited intermolecular charge-transfer bands extending to the near IR region (1000–1500 nm) in addition to intramolecular charge-transfer bands around 600–900 nm characteristic of In–3CNQ compounds. They were characterized as weak charge-transfer solids from estimations of the degree of charge transfer using molecular orbital calculations, bond lengths, and vibration spectra. Intermolecular charge transfer caused a slight increase in the degree of intramolecular charge transfer.
Excited state properties of stilbenes having methoxy substituents at the ortho position of the phenyl ring have been studied and the remarkable methoxy substituent effect to suppress the fluorescence quantum yield depending on the number of methoxy substituent was observed. The fluorescence quantum yield of the trans isomer decreased with increasing number of methoxy substituents and 0.54 for trans-1, 0.13 for trans-2, and 0.011 for trans-3 in benzene.
Electrochemical oxidation of 4-methylcatechol (1) in the presence of, benzoylacetone (2), dibenzoylmethane (3), 3-hydroxy-1H-phenalen-1-one (4), acetylacetone (5), dimedone (6), and 2-acetylcyclohexanone (7) as nucleophiles has been studied in detail by cyclic voltammetry and controlled-potential coulometry. The results indicate that the electrochemically generated quinone participates in Michael addition reaction with 2–7 via various mechanisms to produce new organic compounds. Furthermore, our studies show that the structure of intermediates play a crucial role in product selectivity under controlled-potential conditions. Various types of products were also obtained through the selective oxidation at the surface of a carbon electrode in an undivided cell.
An approach to aromatic compounds using combinations of ring-closing olefin metathesis (RCM), dehydration, oxidation, and tautomerization is reported. The RCM reaction of 1,7-diene-3,5-diols, which were readily prepared by the allylation of aldol products, gave corresponding cyclized products, 4-cyclohexene-1,3-diols, in high yields. The subsequent dehydration or oxidation of 4-cyclohexene-1,3-diols led to versatile substituted benzenes including phenol and resorcinol derivatives.
o-Hydroxybenzophenone (Hbp) chromophores were immobilized on 3-aminopropyl silica gel (SiO2–NH2) by a reaction of succinimidyl 4-(4-benzoyl-3-hydroxyphenoxy)butanoate (2a) and -undecanoate (2b) with SiO2–NH2 to produce microbeads 1a and 1b in 25 and 21% yield, respectively. The bond formation was confirmed by appearance of an absorption at 1550 cm−1 due to the N–H bending of the amide bond in the IR spectra of 1a and 1b. In order to enhance the thermal and photochemical stabilities, the 1a and 1b residual amino group was acetylated by Ac2O in CHCl3 to produce 7a and 7b. Acetylation occurred on the aminopropyl group. However, it did not occur on the phenolic OH group of Hbp from the IR spectra where the absorptions of the bending of the methyl group and the bending of the phenolic OH group appeared at 1375 and 1348 cm−1, respectively. By degradation experiments, it was found that thermal and photochemical stabilities were high in 7a and 7b compared with that of 1a and 1b.
Pulse radiolysis of hexameric nitrite reductase containing the two type 1 Cu sites in a monomer has been carried out. Reduction of the enzyme with N-methylnicotinamide radical follows biphasic kinetics, and the fast and slow phases were assigned to reductions of type 1 CuN and type 1 CuC, respectively.
Wood tar pitch, sometimes referred to as biopitch, is the residue from the distillation of tar recovered during charcoal making processes. The biopitch from Eucalyptus tar, which has guaiacyl and syringyl units in its molecular structure, exhibits novolak behavior and this phenolic oligomer can be cured with hexamethylenetetramine (HMTA). In this work, mixtures of commercial phenolic resins and Eucalyptus tar pitch were cured and characterized by infrared spectroscopy, elemental and thermogravimetric analyses. Their acetone-insoluble contents were determined and their electrical properties were investigated. The effects of pitch and HMTA contents on phenolic resin properties were modelled using statistical techniques. The regions of optimum formulations were indicated. The results showed that pitch decreases the thermal stability and the acetone-insoluble content of the phenolic blends, whereas HMTA addition had an opposite effect. The statistical model applied indicated that, in terms of acetone-insoluble content, phenolic resin can be substituted for pitch up to a composition of 50 wt %. Electrical studies showed that pitch–phenolic blends have insulating properties.