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A new building block ATVTA that uses stiff carbon-carbon triple bonds (A) on 1,2-di(2-thienyl)-ethene (TVT) has been developed. Oligothiophene derivatives S-01 with a TVT unit, S-02 with a 5,5'-diethynyl-2,2'-dithienyl (AT2) unit and S-03 with ATVTA were synthesized to compare their effects in a systematic study. Due to the better π-conjugation extension of the TVT unit, S-01 exhibits the most red-shifted absorption profile among them, whereas S-02 possesses the deepest HOMO level. While the HOMO level of S-03 is down-shifted by 0.02 eV relative to that of S-01, the alkyne linkages can effectively down-shift the HOMO level. By replacing the terminal units of S-03 with stronger electron acceptors, S-04 and S-05 exhibited broader absorption profiles and lower HOMO levels than those of S-03. Organic solar cells based on these molecules were fabricated and an S-03:PC60 BM (1:1, w/w) based device afforded the highest Voc value of 0.96 V and a power conversion efficiency (PCE) of 2.19 %.

A metal-free borylation reaction of electron-rich aryl chlorides, fluorides, mesylates and phosphates under continuous-flow photolytic conditions is reported. The flow setup was designed to facilitate this process efficiently in comparison with the batch mode. Owing to its unique chemical selectivity, mild reaction conditions, good functional group tolerance and substrate scope, this reaction adds a complementary protocol to the current synthetic methods for boronic acid derivatives. The proposed reaction mechanism involves a photolytically generated triplet aryl cation, and DFT calculations suggest that the borylation product is formed in an anion-mediated single step process passing a minimum energy crossing point.

The o-carboranyllithium species Li2C2B10H10 adds to the triple C N bond of a nitrile to afford a stable zwitterionic iminium salt 3 with a nido-C2B9 carborane tether. The novel carborane product 3 has been characterized by means of IR and NMR spectroscopy and mass spectrometry. In addition, the structure of 3 has been studied by a combination of single-crystal X-ray diffraction and density functional theory (DFT) calculations, which proves that the five-membered open face of the nido-carborane cluster and the planar exo-polyhedral five-membered ring have partial conjugation.

The intramolecular arylation of 2-pyrones, 2-pyridones, coumarins and quinolones is reported using PdII precatalyst sources without added phosphine ligands. The excellent yields and convenient reagents enables the formation of various analogues containing these moieties, and access to potential biologically active candidates. Stoichiometric studies were carried out to provide an insight into the oxidation addition step. A switch in regioselectivity, together with a hydrodebromination process, was observed in the case of a 3-bromo-2-pyrone.

The use of various diethynylarene ligands in the synthesis of some metal carbonyl linking clusters is established. New dimeric complexes of osmium [{(μ-CO)Os3(CO)9}2(μ3-η2-diyne)], ruthenium [{(μ-H)Ru3(CO)9}2(μ3-η2,η2-diyne)] or [{(μ-CO)Ru3(CO)9}2(μ3-η2-diyne)] and cobalt [{Co2(CO)6}2(η2-diyne)] (diyne = HC≡CArC≡CH, Ar = 2,7-fluorene, 2,7-fluoren-9-one, bithiazole or bithiophene) have been prepared in good yields from the reaction of [Os3(CO)10(NCMe)2], [Ru3(CO)12] or [Ru3(CO)10(NCMe)2] and [Co2(CO)8] with half an equivalent of the appropriate diethynylarene ligand, respectively. All these cluster compounds have been characterized by IR and 1H NMR spectroscopies and mass spectrometry. The molecular structures of three of them have been determined by X-ray crystallography. For the group 8 osmium and ruthenium analogues, the hexanuclear carbonyl clusters consist of two trinuclear metal cores with the exhibition of the μ3-(η2-||) bonding mode for the acetylene groups when [M3(CO)10(NCMe)2] (M = Ru, Os) was used and the μ3-η2,η2 bonding mode when [Ru3(CO)12] served as the starting cluster. The tetracobalt species possesses two Co2C2 cores adopting the pseudo-tetrahedral geometry having the alkyne bond lying perpendicular to the Co–Co vector in each core. Density functional theory was also used to study the electronic structures of selected molecules.

Three new organic photosensitizers ( HK1 – HK3 ) incorporating functionalized bulky trimer of triarylamine derivatives as the electron donor units, 3,4-ethylenedioxythiophene moiety as the conjugated spacer, and cyanoacrylic acid as the electron acceptor, have been synthesized and the effects of different bulky electron donor substituents on the photovoltaic performances of dye-sensitized solar cells (DSSCs) are investigated accordingly. The DSSC based on HK1 with tris(triphenylamine) electron donor in the absence of the co-adsorbent chenodeoxycholic acid (CDCA) shows the best photovoltaic performance under standard global AM 1.5 sunlight: a short-circuit current density ( J sc ) of 10.41 mA cm −2 , an open-circuit voltage of 0.76 V and a fill factor of 0.65, corresponding to a maximum overall power conversion efficiency (PCE) of 5.11%. However, in the presence of co-adsorbent CDCA, the PCEs of DSSCs based on these photosensitizers, decrease significantly by about 9.7%, which is contrary to the conventional concept that CDCA can improve the efficiency by inhibition of dye aggregation and intermolecular electron recombination. The results demonstrate that the synthesized new organic dyes with bulky dendritic triarylamine and its derivatives as electron-donation units can efficiently suppress dye aggregation without the need of the co-adsorbent and effectively reduce the intramolecular electron recombination in DSSCs.

A multidentate and flexible diolefin-diphosphine ligand, based on the dibenzylidene acetone core, namely dbaphos (1), is reported herein. The ligand adopts an array of different geometries at Pt, Pd and Rh. At Pt(II) the dbaphos ligand forms cis- and trans-diphosphine complexes and can be defined as a wide-angle spanning ligand. (1)H NMR spectroscopic analysis shows that the β-hydrogen of one olefin moiety interacts with the Pt(II) centre (an anagostic interaction), which is supported by DFT calculations. At Pd(0) and Rh(I), the dbaphos ligand exhibits both olefin and phosphine interactions with the metal centres. The Pd(0) complex of dbaphos is dinuclear, with bridging diphosphines. The complex exhibits the coordination of one olefin moiety, which is in dynamic exchange (intramolecular) with the other "free" olefin. The Pd(0) complex of dbaphos reacts with iodobenzene to afford trans-[Pd(II)(dbaphos)I(Ph)]. In the case of Rh(I), dbaphos coordinates to form a structure in which the phosphine and olefin moieties occupy both axial and equatorial sites, which stands in contrast to a related bidentate olefin, phosphine ligand ("Lei" ligand), in which the olefins occupy the equatorial sites and phosphines the axial sites, exclusively.

The Lewis base adduct of B(2)pin(2) and the NHC (1,3-bis(cyclohexyl)imidazol-2-ylidene), which was proposed to act as a source of nucleophilic boryl groups in the β-borylation of α,β-unsaturated ketones, has been isolated, and its solid state structure and solution behavior was studied. In solution, the binding is weak, and NMR spectroscopy reveals a rapid exchange of the NHC between the two boron centers. DFT calculations reveal that the exchange involves dissociation and reassociation of NHC rather than an intramolecular process.

Reaction of [(IPr)Cu-OtBu] (1) with pinB-SiMe(2)Ph (2) leads to the Cu-silyl complex [(IPr)Cu-SiMe(2)Ph] (3). Insertion of CO(2) into the Cu-Si bond of 3 is followed by transformation of the resulting silanecarboxy complex [(IPr)Cu-O(2)CSiMe(2)Ph] (4) to the silanolate complex [(IPr)Cu-OSiMe(2)Ph] (5) via extrusion of CO. As 5 reacts readily with 2 to regenerate 3, a catalytic CO(2) reduction to CO is feasible. The individual steps were studied by in situ(13)C NMR spectroscopy of a series of stoichiometric reactions. Complexes 3, 4, and 5 were isolated and fully characterized, including single-crystal X-ray diffraction studies. Interestingly, the catalytic reduction of CO(2) using silylborane 2 as a stoichiometric reducing agent leads not only to CO and pinB-O-SiMe(2)Ph but also to PhMe(2)Si-CO(2)-SiMe(2)Ph as an additional reduction product.

Reactions of the lithium boryl LiB(R′NCH═CHNR′) (R′ = 2,6-iPr2C6H3), 1, with organohalides (RX) giving RB(R′NCH═CHNR′) and/or XB(R′NCH═CHNR′) were studied computationally using density functional theory calculations at the B3LYP level. Our calculations indicate that the boryl anion in the lithium boryl can undergo nucleophilic attack at an organohalide on the halide-bonded carbon atom and/or the halogen atom to form RB(MeNCH═CHNMe) (an expected SN2 substitution product) and/or XB(MeNCH═CHNMe) (a halogen-abstraction product), respectively. Our energetic calculation results show that an organohalide having a halogen with lower electronegativity and higher ability to engage in hypervalent bonding promotes the halogen-abstraction pathway. Benzyl halides were also found to promote the halogen-abstraction pathway due to conjugation effects that stabilize a benzyl anion in the transition state during the halogen-abstraction process.

The regioselective Pd-catalyzed cyclization of a number of heterocyclic substrates without added phosphine ligands is reported.

The process is of special interest due to the high importance of chiral fluorine compounds in various fields of organic chemistry.

Borylation of quinolines provides an attractive method for the late-stage functionalization of this important heterocycle. The regiochemistry of this reaction is dominated by steric factors but, by undertaking reactions at room temperature, an underlying electronic selectivity becomes apparent, as exemplified by the comparative reactions of 7-halo-2-methylquinoline and 2,7-dimethylquinoline which afford variable amounts of the 5- and 4-borylated products. Similar electronic selectivities are observed for nonsymmetrical 1,2-disubstituted benzenes. The site of borylation can be simply estimated by analysis of the 1H NMR spectrum of the starting material with preferential borylation occurring at the site of the most deshielded sterically accessible hydrogen or carbon atom. Such effects can be linked with C–H acidity. Whilst DFT calculations of the pKa for the C–H bond show good correlation with the observed selectivity, small differences suggest that related alternative, but much more computationally demanding values, such as the M–C bond strength, may be better quantitative predictors of selectivity.