Synthesis,Characterization, and Electronic Structures of Porphyrins Fused with Polycyclic Aromatic Ring Systems

A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro‐Diels–Alder reaction of bicyclo[2.2.2]octadiene‐fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time‐dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π‐molecular orbitals.     

Twisted Polycyclic Arenes from Tetranaphthyldiphenylbenzenes by Controlling the Scholl Reaction with Substituents

Herein, we report two new types of twisted polycyclic arenes ( 2 a , b and 3 a , b ) with constitutionally isomeric π‐backbones, which are synthesized by controlling the Scholl reaction of 1,2,4,5‐tetra(naphth‐2‐yl)‐3,6‐diphenylbenzene ( 1 ) with properly positioned electron‐donating substituents. With a polycyclic backbone containing two [5]helicene and four [4]helicene moieties, 2 a and b are new members of multiple helicenes with interesting stereochemistries. The as‐synthesized 2 a and b are the twisted isomers, and thermal isomerization of twisted‐ 2 b results in anti‐ 2 b , a more stable stereoisomer. Both twisted‐ and anti‐ 2 b have been fully characterized, and the thermal isomerization of twisted‐ 2 b has been studied with ¹H NMR spectroscopy and DFT calculations. Compounds 3 a and b are new members of twistacenes, the benzannulated pentacene backbone of which exhibits an end‐to‐end twist as found from the crystal structure. Twisted‐ and anti‐ 2 b are also found to function as p‐type semiconductors in solution‐processed thin film transistors, whereas the thin films of 3 b appear insulating presumably due to the lack of π–π interactions.     

Construction of Bridged Polycyclic Systems by Polyene Cyclization

A stereoselective construction of bridged tri‐ and tetracyclic systems embedded in some 3,5‐dimethylorsellinic acid (DMOA)‐derived meroterpenoids was achieved by exploiting a polyene cyclization of suitably functionalized epoxyallylsilanes. Both the olefinic substituent on the epoxide and allylic trimethylsilyl (TMS) group were found to play pivotal roles in the success of the present reaction. The fact that the cyclization of monocyclized byproducts did not proceed strongly suggests that the reaction could be a concerted transformation.     

基于二芳炔硫醚的2,6-二芳基-1,4-二噻烯的合成

描述了一种基于二芳炔硫醚(Ar—C≡C—S—C≡C—Ar)底物合成2,6-二芳基-1,4-二噻烯的方法.将二芳炔硫醚和Na2S·9H2O在C2H5OH/C2H5ONa体系中回流反应,以80%~96%的产率合成了一系列2,6-二芳基-1,4-二噻烯化合物.该方法反应条件温和、产率高并且表现出很好的选择性.反应机理涉及硫负离子对底物分子的两个C≡C键的选择性亲核加成,即硫负离子(包括S2-和中间体B硫负离子)总是选择性地加到芳基一侧的炔碳上形成1,4-二噻烯.对化合物1a进行了X线晶体结构解析.分子中的六元杂环呈"船式"构型.C(1)—C(2)和C(1A)—C(2A)具有典型的双键性质,S(1)—C(2)和S(2)—C(1)的键长数则比一般C—S单键稍短,显示硫原子上的孤对电子与C(1)=C(2)双键上的π电子存在一定程度的共轭作用.1a的晶体学参数:属正交晶系,Pnma空间群,a=10.1330(11),b=27.318(3),c=5.5402(6),α=90.00°,β=90.00°,γ=90.00°,V=1533.6(3)3,Z=4,ρcalcd=1.422 g/cm3.最终偏离因子R=0.038,Rw=0.102。     

Palladium-Catalyzed Direct C-3 Alkynylation of Indolizines with (2,2-Dibromovinyl)arenes

The direct C-3 alkynylation of indolizines with (2,2-dibromovinyl)arenes in the presence of palladium catalyst has been developed. This novel protocol showed wide substrate scope with respect to both indolizines and dibromoalkenes. Also this method was characterized with high efficiency and good functional group tolerance.     

A Luminescent Nitrogen‐Containing Polycyclic Aromatic Hydrocarbon Synthesized by Photocyclodehydrogenation with Unprecedented Regioselectivity

We present a nitrogen‐containing polycyclic aromatic hydrocarbon (N‐PAH), namely 12‐methoxy‐9‐(4‐methoxyphenyl)‐5,8‐diphenyl‐4‐(pyridin‐4‐yl)pyreno[1,10,9‐h,i,j]isoquinoline (c‐TPE‐ON), which exhibits high quantum‐yield emission both in solution (blue) and in the solid state (yellow). This molecule was unexpectedly obtained by a three‐fold, highly regioselective photocyclodehydrogenation of a tetraphenylethylene‐derived AIEgen. Based on manifold approaches involving UV/Vis, photoluminescence, and NMR spectroscopy as well as HRMS, we propose a reasonable mechanism for the formation of the disk‐like N‐PAH that is supported by density functional theory calculations. In contrast to most PAHs that are commonly used, our system does not suffer from entire fluorescence quenching in the solid state due to the peripheral aromatic rings preventing π–π stacking interactions, as evidenced by single‐crystal X‐ray analysis. Moreover, its rod‐like microcrystals exhibit excellent optical waveguide properties. Hence, c‐TPE‐ON comprises a N‐PAH with unprecedented luminescent properties and as such is a promising candidate for fabricating organic optoelectronic devices. Our design and synthetic strategy might lead to a more general approach to the preparation of solution‐ and solid‐state luminescent PAHs.     

Delayed lanthanide luminescent Tb(III) complexes formed from lower rim amide functionalised calix[4]arenes

The synthesis and the photophysical studies of a new generation of time resolved luminescent systems based on calix[4]arenes alkylated at the lower rim, capable of hosting lanthanide (III) ions such as terbium and sensitising its emission, are described. Two series of ligands were designed to provide an ideal cavity to host terbium (Tb(III)) and were synthesised in high yields following two novel approaches. The tetra-alkylation, which was achieved in one step using with piperidino- and morpholino-acetamide pendant arms, provides eight donor atoms forming a binding ‘pocket’ at an ideal distance from the metal core to favour the sensitisation via the antenna effect. Of the two ligand series developed, compounds 3 and 4 possess a short spacer between the calix and the amide receptor site. The second series of ligands 6–7, designed with longer pendant amide arms, was synthesised from 2 in two steps through the ester analogue 5. The crystal structure of 3 (and 6 as shown in Supporting Information, available online) is presented. The synthesis and the photophysical studies of the four resulting complexes 3.Tb, 4.Tb, 6.Tb and 7.Tb are described in detail and in each case, successful sensitisation of the terbium emission occurred upon excitation of the phenolic scaffold of the calixarene.     

Synthesis and Characterization of Extended Bis(terpyridine)ruthenium Amino Acids

(Oligopyridine)ruthenium(II) complexes have been widely used in dye sensitized solar cells and other sophisticated optical devices due to their outstanding photophysical properties and their chemical stability. Herein, we describe the longitudinal extension of our previously reported bis(terpyridine)ruthenium(II) amino acid [Ru(tpy–NH₂)(tpy–COOH)]²⁺ (tpy = 4′‐substituted 2,2′:6′,2″‐terpyridine) by insertion of para‐phenylene spacers –C₆H₄– between the terpyridine and the functional groups. The influence of the para‐phenylene spacer on the absorption and emission properties is investigated using UV/Vis absorption and emission spectroscopy and is discussed within a qualitative molecular orbital picture.     

A solvent-free synthesis of (dichloroiodo)arenes from iodoarenes

An efficient solid-state oxidation of iodoarenes, ArI, is described using the urea-hydrogen peroxide adduct (UHP), a stable, inexpensive, and easily handled oxidant. The reactions were complete in 15 min at 85 °C. The melts thus obtained were reacted with excess hydrochloric acid to afford crude (dichloroiodo)arenes, ArICl₂, in 64-98% yields.     

C-H arylation of unactivated arenes with aryl halides catalyzed by cobalt porphyrin

A general procedure for cobalt-catalyzed direct C-H arylation of unactivated arenes has been discovered. This method employs aryl halides as the direct coupling partners with arenes without using any Grignard-type reagents. This catalysis opens a new methodology for the preparation of symmetrical as well as unsymmetrical biaryls in a user-friendly approach.     

Recent advances in transition-metal-catalyzed asymmetric reactions of diazo compounds with electron-rich (hetero-) arenes

The transition-metal-catalyzed reaction of diazo compounds with arenes or heteroarenes is an efficient and straightforward approach to functionalize aromatic compounds. This digest summarizes recent progresses on transition-metal-catalyzed asymmetric reactions of diazo compounds with electron-rich (hetero-) arenes, including C–H functionalization, cascade reaction, cyclopropanation, cycloaddition, Buchner reaction and intramolecular dearomatization.     

An efficient one-pot synthesis of strongly fluorescent (hetero)arenes polysubstituted with amino and cyano groups

An efficient one-pot synthesis simultaneously results in three types of densely substituted mono-, di- and tetracyclic π-systems, which can easily be isolated. Each chromophore presents a strong fluorescence emission, either in the red, green or blue part of the spectrum.     

Direct, easy, and scalable preparation of (diacetoxyiodo)arenes from arenes using potassium peroxodisulfate as the oxidant

The reaction of arenes with potassium peroxodisulfate, elemental iodine, and acetic acid in the presence of concd sulfuric acid, efficiently generates the corresponding (diacetoxyiodo)arenes in good yields, providing an easy, safe, and effective method for preparing (diacetoxyiodo)arenes from arenes and iodine.     

Cyclic Amination onto Aromatic Ring via Radical Pathway with (Diacetoxyiodo)arenes

Sulfonamides of primary amine bearing an aromatic ring at γ-position were treated with (diacetoxyiodo)arene and iodine under irradiation conditions with a tungsten lamp to give the corresponding 1,2,3,4-tetrahydroquinoline derivatives in moderate to good yields.     

Silanol as a removable directing group for the Pd(II)-catalyzed direct olefination of arenes

Need some direction? Silanol was developed as a directing group for the Pd(II)-catalyzed oxidative Heck-type reaction of arenes. A one-pot C-H activation/desilylation process of benzyldiisopropylsilanol was also demonstrated, providing a powerful approach for the synthesis of ortho-alkenyl-substituted alkylarenes. Considering the easily attachable and readily removable properties of the silanol group, this reaction will find broad synthetic applications.     

Photoactive Eu(III) and Tb(III) complexes of calix[4]arenes with pyridine-N-oxide pendant groups

Two calix[4]arenes with four 2-pyridyhnethyl-l-oxide pendant groups at the lower rim have been synthesized, and their Tb(III) and Eu(III) complexes are fluorescent upon UV light excitation at 312 nm. The complexes are not stable in aqueous solution, completely losing their luminescent properties.     

Metallation reactions. Part 35: A change of the regiochemistry in the metallation of (alkylthio)arenes

The metallation reaction of bromo(alkylthio)benzenes is described. The results show the complementarity of these reactions with the metal-hydrogen exchange reaction. In fact, monometallation of bromo(methylthio)benzenes afforded products substituted in para or meta or ortho to the thioethereal function while bimetallation led to αS,para, αS,meta and αS,ortho disubstituted products. Analogously, the monometallation of 4-bromo-(isopropylthio)benzene afforded para-monosubstituted and ortho,para-disubstituted products.     

Synthesis and lead(II) sorption of silica gel-immobilized, di-ionizable calix[4]arenes

Di-ionizable calix[4]arenes with two lower-rim N-(X)sulfonyl carboxamide groups were covalently linked to silica gel via a single attachment on the upper rim. Both the acidity of the ionizable groups (X group variation) and the length of the spacer that joins the ligands to the silica gel matrix were varied. Preliminary evaluation of these new ion-exchange resins for sorption of lead(II) from aqueous solutions was conducted.     

Preparation and Characterization of Layered Compound Zirconium Bis(monohydrogenphosphate) Intercalated with Rare Earth Complex

Rare earth organic complexes usually exhibit intense narrow band emission via anenergy transfer from the ligands to the central rare earth ions under UV excitation.Although rare earth complexes, especially for the complex with 0-diketone, have strongluminescence, their photostability and thermal stability are not very good enough for thephosphor. Therefore, the key problem related to rare earth complex is to try to find asuitable matrix material to trap them. Inorganic solid matrixes are prom…