p-Quaterphenyls laterally substituted with a dimesitylboryl group: a promising class of solid-state blue emitters

A new family of p-quaterphenyls 1-6 laterally substituted with a bulky electron-accepting dimesitylboryl group has been designed and synthesized. These compounds were characterized by X-ray crystallography, UV-vis and fluorescence spectroscopy, and DFT calculations as well as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and cyclic voltammetry (CV). X-ray single-crystal analysis revealed that the p-quaterphenyl main chain framework exhibits a twisted structure due to the steric effect of the lateral boryl group, and the intermolecular interactions are effectively suppressed in the solid state. Despite the significantly twisted main-chain structure, these molecules still display efficient intramolecular charge-transfer emissions with large Stokes shifts. An intriguing finding is that all these molecules show bright fluorescence with good to excellent quantum yields in the blue region in the solid state. In addition, the two representative p-quaterphenyls 3 and 4 containing both the electron-accepting boryl group and the electron-donating carbazolyl (3) or diphenylamino group (4) possess high thermal stability and good oxidation-reduction reversibility, which together with their excellent solid-state fluorescence efficiency make them promising bipolar transporting blue emitters.     

Fe L-edge X-ray absorption spectroscopy of low-spin heme relative to non-heme Fe complexes: delocalization of Fe d-electrons into the porphyrin ligand

Hemes (iron porphyrins) are involved in a range of functions in biology, including electron transfer, small-molecule binding and transport, and O2 activation. The delocalization of the Fe d-electrons into the porphyrin ring and its effect on the redox chemistry and reactivity of these systems has been difficult to study by optical spectroscopies due to the dominant porphyrin pi-->pi(*) transitions, which obscure the metal center. Recently, we have developed a methodology that allows for the interpretation of the multiplet structure of Fe L-edges in terms of differential orbital covalency (i.e., differences in mixing of the d-orbitals with ligand orbitals) using a valence bond configuration interaction (VBCI) model. Applied to low-spin heme systems, this methodology allows experimental determination of the delocalization of the Fe d-electrons into the porphyrin (P) ring in terms of both P-->Fe sigma and pi-donation and Fe-->P pi back-bonding. We find that pi-donation to Fe(III) is much larger than pi back-bonding from Fe(II), indicating that a hole superexchange pathway dominates electron transfer. The implications of the results are also discussed in terms of the differences between heme and non-heme oxygen activation chemistry.     

Visible light-responsive micelles formed from dialkoxyanthracene-containing block copolymers

A class of dialkoxyanthracene-containing diblock copolymers is synthesized which possesses visible light-responsivity. These copolymers can self-assemble into a micellar structure in water. Green visible light (540 nm) is able to scissor these anthracene species and cleave the diblock copolymer into two fragments, inducing disassembly of the self-assembled micelles.     

Application of chelation ion chromatography to the determination of lanthanides in agriculture

Lanthanides are widely present in soil and plant. In this paper, it is the first time that chelation ion chromatography is applied to analyse lanthanides in a series of samples in agriculture. This technique can eliminate bulk quantity of alkali, alkaline earth metals on chelating concentrator column (MetPac CC-1) and eliminate transition metals on cation exchange column (TMC-1) from complex matrices with ammonium acetate buffer while lanthanides are concentrated. It is shown to be capable of separating and determining all lanthanides on mixed-bed ion exchange column (CS5) in a wide variety of sample types with high accuracy. Elution is carried out with a concentration gradient of oxalic acid (Ox) and diglycolic acid (DGA), coupled with post-column spectrophotometric detection with 4-(2-pyridylazo)resorcinol (PAR) at 520 nm. It can determined ng ml(-1) scales of lanthanides. The whole run time after sample injection is about 55 min.     

The geometrical analysis of a predator-prey model with multi-state dependent impulses

Starting from the practical problems of integrated pest management, we establish a predator-prey model for pest control with multi-state dependent impulsive, which adopts two different control methods for two different thresholds. By applying geometry theory of impulsive differential equations and the successor function, we obtain the existence of order one periodic solution. Then the stability of the order one periodic solution is studied by analogue of the Poincar\''{e} criterion. Finally, some numerical simulations are exerted to show the feasibility of the results.     

Simplified aminocoumarin analogues as anticancer agents： Amino isosteric replacement in the noviose moiety resulted in substantial enhancement of antiproliferative activity

Simplified aminocoumarin analogues,either noviosylated or simple basic heterocycle attached 3-amido-coumarin compounds,are known to be promising anticancer agents targeting the C-terminal ATP-binding site of Hsp90.In this study,3’-amino isosteric replacement in the noviose moiety of two known noviose containing Hsp90 C-terminal inhibitors was synthetically realized for the first time.In vitro evaluation of these compounds suggested that the introduction of a basic amino group into the noviose subunit resulted in significant improvement of their cytotoxicities.     

Lattice Boltzmann simulation of phase change and heat transfer characteristics in the multi-layer deposition

The metal droplets deposition method(MDDM) is a rapid prototyping technology, implemented via metallurgy bonding within droplets. The anisotropy of heat transfer and re-melting is caused by an asymmetric deposition process. A lattice Boltzmann method(LBM) model is established to predict the heat transfer and phase change in the multi-layer deposition. The prediction model is verified by the experimental temperature profiles in existing literature. The monitoring points are set to compare the tem...     

Synthetic Studies of an Analogue of HIV-1 Protease Inhibitors of Didemnaketals:Construction of the C1-C8 Intermediate

ThedidenlnaketalsAandBhaveprovedtobesignificantinhibitorstoHIV-Iprotease'.UPtotilepresent.however,nosuccessfulsynthesishasbeenreported.Inconnectiollx'l,lthOLlrs}'ntheticstudiesoftheiranalogLles,wehavereportedasuccesslillsynthesisofthesimilarilltermediateof32.Hereinwewouldpresentanefficientprocedureforthediastereoselectivesynthesisofanotherintermediate4.Basedoiltileretrosyntheticanalysis,theintermediate4couldbesynthesizedfromllaturalI.-(-)-nlelltllollebecauseofthevaltlablechiralCSmethyl.…     

Study on Speciation of Pr(III) in Human Blood Plasma by Computer Simulation

Biological effects of metal are controlled by its in vivo speciation l'2. It is not possible todetermine in vivo speciation of metals with analytical methods so far. The lowmolecular-weight complex distribution of biometal ions in blood plasma was studied bycomputer simulation'. Soluble species of rare earth were also reported 2'3. However,insoluble species of rare earth in blood plasma have not been studied, it is the aim of thispaper to study insoluble species by computer simulation.We impr…