Proton-Template Synthesis of a П─Conjugated Macrocycle and Structure of its Ni_2(Ⅱ)—Complex

metol-free Robson -type macrocycle was synthesized for first time by proton-templation and from that the metal complexes were prepared.By X-ray study the structure of Ni(Ⅱ)-complex was characterized.

A STUDY ON THE STRUCTURAL EFFECT OF DOUBLE BRIDGES CONJUGATED SYSTEMS I.CARBONYL-IMINO SYSTEM

The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.

Synthesis of hollow and mesoporous structured NaYF4：Yb,Er upconversion luminescent nanoparticles for targeted drug delivery

In this paper, we demonstrated a one-step template-free strategy to fabricate a hollow mesoporous structured NaY F4：Yb,Er nanoparticles with excellent upconversion luminescence. Folic acid（FA）, a commonly used cancer-targeting agent, was conjugated on the surface of the nanoparticles based on the presence of free amine groups, which were labeled as NaY F4：Yb,Er-FA HMUCNPs. The properties were extensively studied, which indicated the obtained samples showed a typical hollow mesoporous structure and excellent upconversion luminescence that were useful for cell imaging and drug delivery. The L929 cells viability, hemolysis assay and coagulation test demonstrated good biocompatibility of the samples. The anti-cancer drug doxorubicin hydrochloride（DOX） storage/release properties were demonstrated to be pH-responsive, in which, the drug release might be beneficial at the reduced pH for targeted release and controlled therapy. Moreover, it was found that DOX-loaded NaY F4：Yb,Er-FA HMUCNPs exhibited greater cytotoxicity to KB cells than free DOX due to the specific cell uptake by KB cells via folate receptor-mediate endocytosis. Therefore, the multifunctional nanoparticles combining upconversion luminescent property and hollow mesoporous structure have potential for simultaneous targeted anti-cancer drug delivery and cell imaging.

Structures,stabilities,and IR and ^(13)C-NMR spectra of dihedral fullerenes:A density functional theory study

Dihedral fullerenes are thermodynamically stable molecules with Dnd or Dnh symmetry. Based on experimental findings, two series of dihedral fullerenes with five-fold （C5） and six-fold （C6） symmetry have been studied using density functional theory （DFT）. The DFT calculations showed that for both series the stabilities increased with increasing fullerene size. Structural analyses indicated that the stabilities are related to specific local geometries. In the case of the more abundant C5 series, the presence of approximately planar pentagons and hexagons on the top bowl favors their formation. That is to say, those fuller- enes with small dihedral angles within the polygons are readily formed, because planar hexagons lead to strengthened conjuga- tion which lowers average bonding energies （ABE） and increases thermodynamic stabilities. Non-planar hexagons at equatorial positions in tube-shaped fullerenes have an adverse effect on the conjugation and inhibit their formation. Calculations also demonstrated that fullerenes in the two series, including C50（D5h）, C60（O6h）, C80（O5d）, C96（D6d）, Cllo（D5h）, and Cl20（D5d）, have thermodynamically stable triplet structures with strong conjugation. The calculated IR and 13C NMR spectra of the fullerenes show some similarities and regular trends due to their homogenous structures. The electronic structures indicate that short dou- ble bonds in hexagons with high electron occupancies are readily attacked by electrophilic agents and can also be coordinated by transition metals. Mechanistic discussions suggested that C2 additions and C2 losses constitute reversible processes at high temperature and C2 additions in pentagonal fusions are crucial to the kinetics of the curvature of structures. C3 additions lead to the formation of large fullerenes of other types.

Ultrabroad-band,white light emission from carbon dot-based materials with hybrid fluorescence/phosphorescence for single component white light-emitting diodes

Benefiting from the large Stokes shift between fluorescence and phosphorescence,fluorescence/phosphorescence dual-emitting carbon dots(CDs)have gradually entered at the stage of single-phase white light-emitting diodes(WLEDs)as‘green material'.However,most of the developed dual-emitting CDs have weak phosphorescence,short emission wavelength and narrow emission band,resulting in relatively bluish white light emission and low color rendering index(CRI).Herein,an ultrabroad-band fluorescence/phosphorescence dual-emitting CD-based material(UB-CD@BA)is prepared by thermal treatment of boric acid(BA)and CDs with large conjugated structure.The stable covalent bonding between CDs and BA,as well as three-dimensional spatial restriction effect of selfpolymerization BA molecules around CDs during long-term heating efficiently rigidified the single/triplet excited states of CDs from non-radiative deactivation,thus producing strong dual emissive materials with the high phosphorescence quantum yield of 21%.Remarkable,the prepared UB-CD@BA powders exhibit bright pure white light emission with Commission Internationale de l'Eclairage(CIE)coordinates of(0.32,0.33)and the highest reported full width at half maximum of 250 nm.Based on the unique characteristics of UB-CD@BA,it was used as a color conversion layer to prepare a WLED with CIE coordinates of(0.35,0.33)and the CRI value of 87.

New advances in small molecule hole-transporting materials for perovskite solar cells

Organic π-functional molecules are the foundation and basic component of organic optoelectronic devices.For example,for ideal carrier transporting materials,extended π-conjugation and ordered π-πstacking are necessary to enhance the charge mobility and achieve desirable results.As a promising way to convert sunlight into electricity,organometal halide perovskite solar cells（PSCs） have captured a lot of attention due to its predominant merits especially in the aspect of remarkable photovoltaic performance and much potentially low production cost.For conventional planar PSC structure,hole-transporting layer which typically consists of organic π-functional materials plays a key role in suppressing holeelectron pair recombination,promoting charge transporting and ensuring ohmic contact of back electrode.Considering the key roles of HTMs and its soaring progress in recent years,here,we will summarize recent progress in small organic π-functional materials from its diverse functions in PSCs.Besides,aiming to further promote the development of organic π-functional molecules and HTMs,a promising direction toward highly efficient HTMs will also be discussed.

Influence of the alkyl side chain length on the room-temperature phosphorescence of organic copolymers

Pure organic room-temperature phosphorescence(RTP)materials have attracted wide attention owing to their excellent luminescent properties and great potential in various applications.In this work,iminostilbene and its analogues are applied to realize RTP emission by copolymerizing with acrylamide.It can be concluded that the growth of alkane chain in monomers can enhance the lifetime and photoluminescence quantum yield of RTP emission,and polymers with the larger conjugated structure of the monomer show a longer RTP emission wavelength.This work provides a series of new pure organic RTP materials and might provide new thoughts for designing more advanced and superior RTP materials.

STRUCTURAL EFFECT IN FORKED CONJUGATIVE SYSTEMS——BIFURCATION-TYPE OF FORKED POLYENIC NITRILES,CARBOXYLIC ACIDS AND ESTERS

Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts for the methyl-, methylene- and beta-protons havebeen found to conform very well to the rule of homologous linearity. The mass spectra forthe α-cyano polyenic ester series show strong peaks for the fragments of M-COOEt but noneof M-CN, indicating that the CN group seems to be in stronger conjugation with the poly-enic chain than the COOEt group does. In all the forked series studided, a red shift in electronic spectra is brought about upon the introduction of an electron-attractive branching group, just like the case of introducing an electron-repelling substituent. This has been taken as an indication of the predominance of themolecular integrality over the group characteristics. By means of the method of similar triangles between a homologous line for a linearseries and that for the corresponding forked compounds, the equivalent △Ns for a branching group may be calculated with accuracy. Based on the value of this equivalent, the substituentnature of the structural effect of the branching group has been inferred. The electronic absorption maxima for four series of the forked compounds have been cal-culated by means of the extended homologous equation for the corresponding linear compounds.With an appropriate correction for the positional effect of the substituent equivalent, the cal-culated wavelengths agree generally with experimental data within ± 7nm.