• Journal of Pharmaceutical Investigation
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• v.23 no.3
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• pp.119-125
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• 1993

The protein binding of salicylate analogs has been investigated by equilibrium dialysis. A series of binding experiments were performed in order to elucidate the effects of physicochemical properties of salicylate analogs on the binding with bovine serum albumin. Attempts to correlate affinity constants with capacity factor, steric factor and Hammett ${\sigma}$ values suggested hydrophobic forces to be involved in the binding of salicylate analogs. Steric factor contributes to binding process partly, whereas electronic interaction appears to be insignificant.

• Journal of the Korean Chemical Society
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• v.46 no.3
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• pp.225-228
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• 2002

Poly-o-toluidine (POT) was chemically and electrochemically synthesized for the study of the electronic and steric effect of methyl substituents. It was found that the steric effect was dominant in POT. The IP 4.95 eV, EA 3.24 eV, Eg 1.71 eV of POT were found by the CV (Cyclic Voltammetry) and CCPSA (Constant Current Potentiometric Stripping Analysis).

• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.133-135
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• 2007

• Journal of the Korean Chemical Society
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• v.46 no.3
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• pp.229-232
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• 2002

Poly-o-toluidine (POT) was chemically and electrochemically synthesized for the study of electronic and steric effect of methyl substituents. The turn-on voltage of organic light emitting diode (OLED) was 9~14 V. ITO/POT/Al structured OLED were fabricated with various oxidation states of POT. PL, I-V characteristics and EL spectra were investigated.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.193-196
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• 1987

The gas phase pyrolyses of eight esters have been studied by MNDO-MO method. In the ethylformate pyrolysis, ${\alpha}$-methylation had a steric releasing effect whereas ${\beta}$-methylation had a steric crowding in the transition state; the latter, however, is over-compensated by a greater electronic repulsion resulting in a net steric releasing effect. Considerations of formal charges and geometrical changes involved in the activation led us to propose a pyrolysis mechanism in which a preequilibrium of acidic proton transfer is followed by the rate-limiting bond polarization of $C_{\alpha}$-O bond in a cyclic transition state.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1884-1890
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• 2011

A series of Ni(II) and Pd(II) complexes bearing N4-type tetradentate ligands, [Ni($X^1X^2$-6-$Me_2bpb$) 1] and [Pd($X^1X^2$-6-$Me_2bpb$) 2]; 6-$Me_2bpb$ = N,N'-(o-phenylene)bis(6-methylpyridine-2-carboxamidate), $X^1$ = Cl, H, or $CH_3$, $X^2$ = $NO_2$, Cl, F, H, $CH_3$, or $OCH_3$) were designed, synthesized, and characterized to investigate electronic and steric effects of ligand on the norbornene polymerization catalysts. Using modified methylaluminoxanes as an activator, the complexes exhibited high catalytic activities for the polymerization of norbornene and the nickel complexes exhibited better catalytic activity the palladium complexes. Ni complex 1a with $NO_2$ group on the benzene ring showed the highest catalytic activity of $4.9{\times}10^6$ g of PNBEs/$mol_{Ni}{\cdot}h$ and molecular weight of $15.28{\times}10^5$ g/mol with PDI < 2.30. Complexes with electron-withdrawing groups are more thermally stable (> 100 $^{\circ}C$), and tend to afford higher polymerization productivities than the ones having electron-donating groups. Amorphous polynorbornenes were obtained with good solubility in halogenated aromatic solvents. A vinyl addition mechanism has been proposed for the catalytic polymerization.

• Journal of Photoscience
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• v.3 no.1
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• pp.43-47
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• 1996

The 77 K emission and excitation, and room-temperature UV-visible spectra of $\Lambda$-fac[Cr(L-ala)$_3$] (ala = alanine anion) have been measured. The ten electronic transitions due to spinallowed and spin-forbidden are assigned. With the observed electronic transition energies, ligand field optimizations have been performed to determine the bonding properties of L-alanine anion toward chromium(III). The angular overlap model (AOM) parameters obtained indicate that it is electron-donating ligand which has values of e$_{\sigma}O$, e$_{\pi}O$, and e$_{\sigma}N$ slightly lower than those of glycine anion (gly). It seem that the decrease of the ligand field properties is due to steric effect of extra methyl group and inductive effect of adjacent carbonyl group.

• Transactions on Electrical and Electronic Materials
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• v.7 no.3
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• pp.112-117
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• 2006

In this paper we present that the effects of polymer adsorption on stabilities and CMP performance of ceria abrasive particles. Characterization of ceria abrasive particles in the presence of poly(vinyl pyrrolidone) (PVP) was performed by the measurements of adsorbed amounts of PVP, average sizes, and the back scattering intensities of the ceria abrasive particles as functions of PVP molecular weight and PVP concentration. The ceria abrasive particles in the presence of PVP were used to polish $SiO_2\;and\;Si_3N_4$ films deposited on Si wafers in order to understand the effect of PVP adsorption on chemical mechanical polishing (CMP) performance, together with ceria abrasive particles without PVP. Adsorption of PVP on the ceria abrasive particles enhanced the stability of ceria abrasive particles due to steric stabilization of the thick adsorbed layer of PVP. Removal rates of the deposited $SiO_2\;and\;Si_3N_4$ films by the ceria abrasive particles in the presence of PVP were much lower than those in the absence of PVP and their magnitudes were decreased with an increase in the concentration of free PVP chains in the dispersion media. This suggests that the CMP performance in the presence of PVP could be mainly controlled by the hydrodynamic interactions between the adsorbed PVP chains and the free ones. Moreover, the molecular weight dependence of PVP on the removal rates of the deposited films was hardly observed. On the other hand, high removal rate selectivity between the deposited films in the presence of PVP was not observed.

• Journal of Pharmaceutical Investigation
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• v.22 no.3
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• pp.65-76
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• 1992

The superoxide dismutase (SOD)-mimetic activities of copper complexes of a series of salicylic acid (SA) analogs were tested and compared to the activity of bovine erythrocyte SOD using ferricytochrome c reduction assay. Stability constants of copper complexes were measured potentiometrically using SCOGS2 program. In the presence of 10 g/l albumin, all the copper complexes lost their SOD mimetic activities. Multiple regression analysis was employed for the statistical comparisons between the SOD mimetic activity and their physicochemical properties. Correlation exists for the SOD mimetic activity and steric parameter $(E_s)$ and/or electronic parameter $({\Sigma}{\sigma})$ in xanthine/xanthine oxidase (XOD) system, demonstrating that E, plays a key role in SOD activity whereas ${\Sigma}{\sigma}$ influences it to a lesser extent. The protective effect of copper complexes against membrane damage was measured by counting D-glucose released frm $EG_s$. D-glucose and XOD were entrapped within $EG_s$ and acetaldehyde was used as a substrate for XOD. In this membrane model system using $EG_s$, hydrophobic parameter $({\Sigma}{\pi})$ is of most importance, producing parabolic equation while $E_s$, and ${\Sigma}{\sigma}$ appear to playa minor role in protection against D-glucose release. In summary, to design an efficient SOD mimetic, stability, steric factor, lipophilicity and redox potential should be considered.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1121-1127
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• 2014

The design, synthesis, and structural characterization of two new palladium complexes based on Schiff base ligands is reported; $[Pd(L1)_2]$ (1) and $[Pd(L2)_2]$ (2), [HL1 = 2-((E)-(2,6-diethylphenylimino)methyl)-4,6-dibromophenol, L2 = (E)-N-benzylidene-2,6-diethylbenzenamine], which are obtained by functionalizing Schiff base ligands with or without electron-withdrawing groups. Both compounds are mononuclear structures. Comparisons are made to the compounds 1 and 2 to analyze and understand the effect of electron-withdrawing groups. Antibacterial activity studies indicate the electron-withdrawing groups on Schiff base ligands enhance antibacterial activity. Catalytic activity, however, is reduced due to the enhanced steric-hindrance of the electron-withdrawing groups. Electronic absorption and emission properties of HL1, L2, 1 and 2 are also reported.