Tuning of the charge and energy transfer in ternary CdSe/poly(3-methylthiophene)/poly(3-hexylthiophene) nanocomposite system

Composite CdSe:poly(3-methylthiophene) (P3MT) nanoparticles have been synthesized via polymerization of 3-methylthiophene (3MT) in the presence of CdSe particles of nanorod or dot-like morphology and dispersed in the poly(3-hexylthiophene) (P3HT) matrix. The effect of the P3MT layer to mediate charge and energy transfer between CdSe and P3HT in the ternary nanocomposite system has been studied using electronic absorption, photoluminescence spectroscopy, and current–voltage measurements. The energy level diagram of the composite system has been deduced based on optical and electrochemical data of the separate components of the system. The contribution of the low- and high-molecular fractions of P3MT to control the charge transfer in order to optimize the intermediary role of P3MT is analyzed. Particularly, it was shown that excitation of the low-molecular P3MT leads to energy transfer to both CdSe and P3HT components, and it also serves as a barrier against recombination of electrons and holes separated at CdSe and P3HT, respectively. Thus, the role of the P3MT interlayer in assisting the charge separation and increasing an open-circuit voltage in the photovoltaic cell based on the ternary system is demonstrated.     

Sandwich Double‐Decker Lanthanide(III) “Intracavity” Complexes Based on Clamshell‐Type Phthalocyanine Ligands: Synthesis,Spectral, Electrochemical,and Spectroelectrochemical Investigations

Phthalocyanine compounds of novel type based on a bridged bis‐ligand, denoted “intracavity” complexes, have been prepared. Complexation of clamshell ligand 1,1′‐[benzene‐1,2‐diylbis(methanediyloxy)]bis[9(10),16(17),23(24)‐tri‐tert‐butylphthalocyanine] (^clam,tBuPc₂H₄, 1 ) with lanthanide(III) salts [Ln(acac)₃] ? n H₂O (Ln=Eu, Dy, Lu; acetylacetonate) led to formation of double‐deckers ^clam,tBuPc₂Ln ( 2 a – c ). Formation of high molecular weight oligophthalocyanine complexes was demonstrated as well. The presence of an intramolecular covalent bridge affecting the relative arrangement of macrocycles was shown to result in specific physicochemical properties. A combination of UV/Vis/NIR and NMR spectroscopy, MALDI‐TOF mass‐spectrometry, cyclic voltammetry, and spectroelectrochemistry provided unambiguous characterization of the freshly prepared bis‐phthalocyanines, and also revealed intrinsic peculiarities in the structure–property relationship, which were supported by theoretical calculations. Unexpected NMR activity of the paramagnetic dysprosium complex 2 b in the neutral π‐radical form was observed and examined as well.     

Total Synthesis of Indole‐Derived Allocolchicine Analogues Exhibiting Strong Apoptosis‐Inducing Activity

A series of novel pyrrolo‐allocolchicine derivatives (containing a 1‐methyl‐1H‐indol‐5‐yl moiety replacing ring C) was synthesized. The tetracyclic ring system was constructed by Suzuki–Miyaura cross‐coupling of a 1‐methylindole‐5‐boronate with an ortho‐iodo‐dihydrocinnamic acid derivative and subsequent intramolecular Friedel–Crafts acylation. After reduction of the resulting ketone, the nitrogen functionality was introduced in a Mitsunobu‐type reaction by using zinc azide followed by LiAlH₄ reduction. Structural assignments were supported by X‐ray crystallography. The compounds synthesized were then tested against BJAB tumor cells and found to exhibit pronounced cytotoxic activity (proliferation inhibition and apoptosis induction). The ketone 24 b was even active at sub‐nanomolar concentration. In addition, the antitumor potential of the compounds was confirmed by using B lymphoid cell lines.     

Theoretical prediction of S-H bond rupture in methanethiol upon interaction with gold

Organic thiols are known to react with gold surface to form self-assembled monolayers (SAMs), which can be used to produce materials with highly attractive properties. Although the structure of various SAMs is widely investigated, some aspects of their formation still represent a matter of debate. One of these aspects is the mechanism of S-H bond dissociation in thiols upon interaction with gold. This work presents a new suggestion for this mechanism on the basis of DFT study of methanethiol interaction with a single gold atom and a Au(20) cluster. The reaction path of dissociation is found to be qualitatively independent of the model employed. However, the highest activation barrier of S-H bond dissociation on the single gold atom (12.9 kcal/mol) is considerably lower than that on the Au(20) cluster (28.9 kcal/mol), which can be attributed to the higher extent of gold unsaturation. The energy barrier of S-H cleavage decreases by 4.6 kcal/mol in the presence of the second methanethiol molecule at the same adsorption site on the model gold atom. In the case of the Au(20) cluster we have observed the phenomenon of hydrogen transfer from one methanethiol molecule to another, which allows reducing the energy barrier of dissociation by 9.1 kcal/mol. This indicates the possibility of the "relay" hydrogen transfer to be the key step of the thiol adsorption observed for the SAMs systems.     

[N,N′‐Bis(2,6‐diisopropylphenyl)acenaphthene‐1,2‐diimine‐1κ2N,N′]heptacarbonyl‐1κC,2κ3C,3κ3C‐di‐μ3‐tellurido‐triiiron(II)(2 Fe—Fe)

The sterically hindered title complex, [Fe₃Te₂(C₃₆H₄₀N₂)(CO)₇], was obtained by substitution of two carbonyl groups in the [Fe₃(μ₃‐Te)₂(CO)₉] cluster by the bulky redox‐active N,N′‐bis(2,6‐diisopropylphenyl)acenaphthene‐1,2‐diimine (dpp‐BIAN) ligand. The asymmetric unit contains two molecules of the same geometry. The C=N bond lengths in dpp‐BIAN indicate a rather low level of electron transfer from the cluster core to the dpp‐BIAN ligand.     

Bounds for steady water waves with vorticity

The two-dimensional free-boundary problem describing steady gravity waves with vorticity on water of finite depth is considered. Bounds on the free-surface profiles and on the total head are obtained under minimal assumptions about properties of solutions to the problem and the vorticity distribution.     

Generators and commutators in finite groups; abstract quotients of compact groups

The first part of the paper establishes results about products of commutators in a d-generator finite group G, for example: if H?G=??g ₁,??,g _r ?? then every element of the subgroup [H,G] is a product of f(r) factors of the form $[h_{1},g_{1}][h_{1}^{\prime},g_{1}^{-1}]\ldots\lbrack h_{r},g_{r}][h_{r}^{\prime },g_{r}^{-1}]$ with $h_{1},h_{1}^{\prime},\ldots,\allowbreak h_{r},h_{r}^{\prime }\in H$ . Under certain conditions on H, a similar conclusion holds with the significantly weaker hypothesis that G=H??g ₁,??,g _r ??, where f(r) is replaced by f ₁(d,r). The results are applied in the second part of the paper to the study of normal subgroups in finitely generated profinite groups, and in more general compact groups. Results include the characterization of (topologically) finitely generated compact groups which have a countably infinite image, and of those which have a virtually dense normal subgroup of infinite index. As a corollary it is deduced that a compact group cannot have a finitely generated infinite abstract quotient.     

TM7TM'6B8 (TM = Ta, Nb; TM' = Ru, Rh, Ir): new compounds with [B6] ring polyanions

The ternary boron compounds TM(7)TM'(6)B(8) (TM = Ta, Nb; TM' = Ru, Rh, Ir) were prepared by high-temperature thermal treatment of mixtures of the elements. An analysis of the chemical bonding by the electron density/electron localizability approach reveals formation of covalently bonded polyanions [B(6)] and [TM'(6)B(2)]. The cationic part of the structure contains separated TM cations. In agreement with the chemical bonding analysis and band structure calculations, all TM(7)TM'(6)B(8) compounds are metallic Pauli-paramagnets (TM' = Ru, Rh) or diamagnets (TM' = Ir).     

Phosphites and diamidophosphites based on mono-ethers of BINOL: a comparison of enantioselectivity in asymmetric catalytic reactions

Novel P-monodentate phosphite-type ligands have been synthesized in one step from BINOL mono-tosylate and BINOL mono-(?)-menthylcarbonate. The use of these ligands provides up to 96% ee in Pd-catalyzed asymmetric allylic substitution of (E)-1,3-diphenylallyl acetate and up to 99% ee in Rh-catalyzed asymmetric addition of phenylboronic acid to cyclohex-2-enone. The influence of the structural modules such as the nature of phosphorus-containing ring or exocyclic substituent on the enantioselectivity is discussed.