Synthesis, antihistaminic action and theoretical studies of (4-methoxybenzyl)(1,4,5,6-tetrahydropirimidin-2-yl)amine hydroiodide

In this study, (4-methoxybenzyl)(1,4,5,6-tetrahydropyrimidin-2-yl)amine hydroiodide (2) was synthesized by reaction of 2-methylmercapto-1,4,5,6-tetrahydropyrimidine hydroiodide (1) and 4-methoxybenzylamine. The synthesized compound was tested for its in vitro H1-antihistaminic activity on guinea pig trachea. A promising bronchorelaxant effect of 2 was observed in histamine-contracted guinea pig tracheal chain via H1 receptor antagonism. In addition, the molecular geometry and gauge including atomic orbital (GIAO) ¹H chemical shift values of the title compound in the ground state were calculated using the density functional method (DFT/UB3LYP) and Hartree–Fock (HF) approach using 6–311G+(d), 6–311G+(d,p), LANL2DZ, DGDZVP, and DGDZVP2 basis sets and compared with the experimental data. According to the experimental and theoretical results, HF/6–311G+(d) showed a better fit to experimental values in evaluating ¹H-nuclear magnetic resonance (NMR) chemical shift values. Theoretical studies supported our findings, revealing the N₁₂ atom as the most nucleophilic. In addition, other structures of the compound such as the aromatic ring and OCH₃ group increased this property.     

Synthesis of sterically constrained tricyclic pyrrolidinyl alcohol ligands for the enantioselective ethylation of aryl aldehydes: assessment of the influence of ring strain and N-alkyl chain length on asymmetric induction

A series of chiral sterically constrained tricyclic pyrrolidinyl alcohol ligands were synthesized from the appropriate amino acids, and a comparative study of the activity and selectivity of the ligands for the enantioselective ethylation of aromatic aldehydes was carried out. The results obtained were compared with those previously reported for related monocyclic analogues; it was found that the bicyclo[2.2.2]octane backbone fused to pyrrolidine and the groups attached to the carbinol centre, as well as the chain length of the β-amino alcohol, had a marked effect on the enantioselectivity. The enantioselective addition of dialkylzincs to aryl aldehydes in the presence of ligands with diethyl substituents on the carbinol carbon afforded (R)-sec-alcohols in up to 99% enantiomeric excess (ee).     

A first-principles studies on TlX (X=P, As)

We present an ab initio study of the structural, electronic and thermodynamic properties of TlX(X=P,As). The plane-wave pseudopotential approach to the density-functional theory within the LDA and GGA approximations implemented in VASP (Viena Ab-initio Simulation Package) is used. The calculated lattice parameter, elastic constants, and band structures are compared with other available theoretical results, and good agreement is obtained. In addition, we have calculated the transition pressure (P _t ) from zinc-blende (ZB) to (rock-salt) NaCl structures, and have examined some thermodynamic properties.      

Can Hg(II) be Determined via Quenching of the Emission of Green Fluorescent Protein from <Emphasis Type="Italic">Anemonia sulcata</Emphasis> var. <Emphasis Type="Italic">smaragdina</Emphasis>?

Anemonia sulcata var. smaragdina is a widely distributed Cnidarian species along Turkish coastlines. It is also a well-known example of a facultative symbiotic life form in sea ecosystems. Green fluorescent proteins (GFPs) in Anemonia sulcata var. smaragdina have vital roles in this symbiotic form. The fluorescence quenching by Hg(II) in the supernatants obtained from A. sulcata var. smaragdina was shown in this study. According to results, there was a statistical significant relationship (R ² = 0.9913) between increased Hg(II) concentration and decreased fluorescence intensity of GFP supernatants obtained from A. sulcata var. smaragdina. Mn(II), Fe(II), and Al(II) showed no interference effect and did not change the fluorescence intensity of GFP supernatants obtained from A. sulcata var. smaragdina. In conclusion, the fluorescence quenching of GFPs by Hg(II) can be a novel method to determine the Hg(II) levels in aqueous solution. Therefore, further researches are strongly warranted because of the possible potential applications of the fluorescence quenching of GFPs by Hg(II).     

Selective Hg(II) sensing with improved Stokes shift by coupling the internal charge transfer process to excitation energy transfer

Versatile chemistry of the Bodipy chromophore allows modular assembly of an excitation energy donor, acceptor, and a cation selective ligand in just a couple of steps. The new approach should be applicable in other designs which target molecular sensors with large Stokes shifts and red to near IR emission.     

Modulation of boradiazaindacene emission by cation-mediated oxidative PET

[reaction: see text] Bright green boradiazaindacene fluorescence is quenched by an oxidative photoinduced electron transfer (PET) from the excited state fluorophore to the bipyridyl unit complexed to metal cations. The closed shell diamagnetic cation Zn(II) is one of the most effective quenchers of fluorescence in this system, demonstrating that the quenching is not simply related to the facilitated intersystem crossing. The molecule also acts as a NOR logic gate with two chemical inputs, TFA and Zn(II).