Intercalators. 1. Nature of stacking interactions between intercalators (ethidium, daunomycin, ellipticine, and 4',6-diaminide-2-phenylindole) and DNA base pairs. Ab initio quantum chemical, density functional theory, and empirical potential study

Properties of isolated intercalators (ethidium (E), daunomycin (D), ellipticine (EL), and 4,6'-diaminide-2-phenylindole (DAPI)) and their stacking interactions with adenine...thymine (AT) and guanine...cytosine (GC) nucleic acid base pairs were investigated by means of a nonempirical correlated ab initio method. All intercalators exhibit large charge delocalization, and none of them (including the DAPI dication) exhibits a site with dominant charge. All intercalators have large polarizability and are good electron acceptors, while base pairs are good electron donors. MP2/6-31G*(0.25) stabilization energies of intercalator...base pair complexes are large (E...AT, 22.4 kcal/mol; D...GC, 17.8 kcal/mol; EL...GC, 18.2 kcal/mol; DAPI...GC, 21.1 kcal/mol) and are well reproduced by modified AMBER potential (van der Waals radii of intercalator atoms are enlarged and their energy depths are increased). Standard AMBER potential underestimates binding, especially for DAPI-containing complexes. Because the DAPI dication is the best electron acceptor (among all intercalators studied), this difference is explained by the importance of the charge-transfer term, which is not included in the AMBER potential. For the neutral EL molecule, the standard AMBER force field provides correct results. The Hartree-Fock and DFT/B3LYP methods, not covering the dispersion energy, fail completely to reveal any energy minimum at the potential energy curve of the E...AT complex, and these methods thus cannot be recommended for a study of intercalation process. On the other hand, an approximate version of the DFT method, which was extended to cover London dispersion energy, yields for all complexes very good stabilization energies that are well comparable with referenced ab initio data. Besides the vertical dependence of the interaction, an energy twist dependence of the interaction energy was also investigated by a reference correlated ab initio method and empirical potentials. It is concluded that, despite the cationic (E +1, D +1, DAPI +2) or polar (EL) character of the intercalators investigated, it is the dispersion energy which predominantly contributes to the stability of intercalator...base pair complexes. Any procedure which does not cover dispersion energy is thus not suitable for studying the process of intercalation.     

Synthesis and Structure of O-Ethyl S-Hydrogen Isoquinolin-1-ylcarbonothioimidate

1 INTRODUCTION Isoquinoline and its derivatives have attracted much attention due to their physiological and phar- macological activities including antibacterial, antitu- mor, etc[1~3]. A lot of investigations in this field have been focused on the syntheses and applications in physiology and pharmacy of isoquinoline and its derivatives[4, 5]. Recently, a novel class of 1-subs- tituted isoquinolines or triazoloquinazolines deriva- tives have been identified as potential antagonists for the…     

Hydrothermal Synthesis and Structure of a Novel 1-D Mn(II) Compound with Carboxlyto and Imidazole Ligands

1 INTRODUCTION Mn complexes containing carboxylato ligands attract considerable interest due to the richness in structural chemistry[1～4] and potential applications in catalysis[5, 6], for example, some highly efficient Mn catalase mimics[7, 8]. Recently, we focus on the hy- drothermal synthesis of manganiferous coordination polymers using multiple carboxylato and nitrogen- containing ligands[9, 10]. As one of the interesting bridge ligands, terephthalato ligand (ta) can provide multipl…     

Crystal and Molecular Structure of 4-Hydroxy-3-Methoxy-4-N-Methylstilbazonium Iodide C_(15) H_(16) NO_2 +·I~-CrystalandMolecularS

１　ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｓｅａｒｃｈｏｎＳＨＧｅｆｆｅｃｔｈａｓｂｅｅｎｏｎａｒｅｍａｒｋａｂｌｅｐｏｓｉｔｉｏｎｉｎｏｒｇａｎｉｃｎｏｎｌｉｎｅａｒｏｐｔｉｃａｌ（ＮＬＯ）ｍａｔｅｒｉａｌｓｆｉｅｌｄ．Ｔｈｅｃｏｎｊｕｇａｔｅｄｄｅｌｏｃａｌｉｚｅｄπｅｌｅｃｔｒｏｎｓｐｏｓｓｉｂｌｙｒｅｓｕｌｔｉｎｔｈｅｓｅｃｏｎｄ－ｏｒｄｅｒＮＬＯｐｒｏｐｅｒｔｙｏｆｏｒｇａｎｉｃｃｏｍｐｏｕｎｄｓ,ｓｏａｎｕｍｂｅｒｏｆｎｉｔｒｏａｎｉｌｉｎｅｄｅｒｉｖａｔｉｖｅｓ,ｓｕｃｈａｓ２－ｍｅｔｈｙｌ…     

SHOCK COMPRESSION BEHAVIOR OF BROMOFORM

ＳＨＯＣＫＣＯＭＰＲＥＳＳＩＯＮＢＥＨＡＶＩＯＲＯＦＢＲＯＭＯＦＯＲＭＰｅｎｇＳｈａｎｇｑｉａｎｇａ，ｂ，ｃＪｉｎｇＦｕｑｉａｎａ，ｂＨｕＪｉｎｂｉａｏａ，ｂＧｏｕＱｉｎｇｑｕａｎｂａ．ＬａｂｆｏｒＳｈｏｃｋＷａｖｅａｎｄＤｅｔｏｎａｔｉｏｎＰｈｙ...     

Synthesis and Crystal Structure of a Novel Complex [Ag(NIT3Py)_3]·(ClO_4)(H_2O)

1 INTRODUCTION Nitronyl nitroxide radicals (NITR), stable organic radicals, have played an important role in the design and synthesis of molecular magnetic materials[1, 2]. However, nitronyl nitroxide radicals are poor elec- tron-donor ligands and their coordination ability is limited. Recently, it has led to the development of functionalized nitronyl nitroxide radicals in which a strong coligand is incorporated. Due to the strong coordinate ability of nitrogen atom from pryidinyl ring,…     

Adsorption and Reaction of CN ＋ O → OCN on Cu（100） Surface： A Density Functional Theory Study

1 INTRODUCTION The determination of structures of adsorbed cya- nide (CN) and cyanate (OCN) on transition metal surfaces is important for understanding their bon- ding and reactivity in catalysis and other surface phenomena[1～4]. During the past decade, the adsorp- tion of CN and CN-containing on transition metal surfaces has received a great deal of attention in both experimental[5～20] and theoretical[1～5, 13, 20～33] inves-tigations, and the previous work about the adsorp- tion of…     

A Novel Three-dimensional Inorganic Open-framework Constructed from [Mo_4O_(16)]_n ~(8n-) Chains Linked through Ag~+

1 INTRODUCTION even three-dimensional (3-D) extended solid frame- works in appropriate ways is a major challenge in The syntheses and characterizations of novel po- POMs chemistry. Based on the fact that POMs fra- lyoxometalates (POMs) have currently attached in- meworks with high electronic density can act as un- creasing interest owing to not only enormous variety usually effective ligands to coordinate second tran- of intriguing structural topologies, but also their fas- sition meta…     

Tungstate as complex-forming reagent facilitating separation of selected polyphenols by capillary electrophoresis and its comparison with borate

A novel electrophoretic BGE containing tungstate as complex-forming reagent is suitable for the separation of polyphenols. Similar to molybdate-containing BGE reported earlier (cf. M. Polásek, et al.., Talanta 2006, 69, 192) addition of tungstate to BGE affects significantly migration of compounds/ligands with vicinal -OH groups due to the formation of negatively charged complexes involving W(VI) as central ion. Baseline separation of mixtures of flavonoids (apigenin, luteolin, hyperoside, quercetin, and rutin) and phenolic acids (chlorogenic and p-coumaric acid) was achieved within 15 min with optimized BGE of pH 7.4 containing 50 mM N-(2-hydroxyethyl)piperazine-2'-(2-ethanesulfonic acid) (HEPES), 2.2 mM tungstate, and 25% v/v of methanol. The separation was performed in a 75 cm (effective length 42 cm)x 75 microm id uncoated fused-silica capillary at 30 kV with spectrophotometric detection at 275 nm. The calibration curves were rectilinear for 25-175 microg/mL of all analytes (cinnamic acid as the internal standard). The LODs ranged from 1.8 to 6 microg/mL for all analytes except for chlorogenic acid. Intraday precision (n = 6) of migration times (RSD < or = 1.2%) and peak areas (RSD < or = 5.6%) was evaluated. The tungstate-based BGEs can be alternatively utilized for the analysis of polyphenols at considerably lower pH than with conventional alkaline borate-based BGEs.     

Density Functional Theory Study on the Adsorption of HCNH and CNH2 on Cu（100） Surface

The HCNH and CNH2 adsorption on different coordination sites of Cu（100） was theoretically studied considering the cluster approach. The present calculations show that the bridge site is the most favorite for CNH2 perpendicularly adsorbed on the Cu（100） surface via the C atom. For HCNH absorbed on the Cu（100） surface, the parallel adsorption mode with the C and N atoms nearly directly above the adjacent top sites of Cu（100） surface is the most favored. Both CNH2 and HCNH are strongly bound to the Cu（100） surface with CNH2 which is lightly stable （2.51 kJ·mol^-1）, indicating that both species may be co-adsorbed on the Cu（100） surface.