New Penta(tetrathiafulvalenyl)[60]fullerenes for Supramolecular Materials

New penta(organo)fullerenes donor–acceptor systems bearing five tetrathiafulvalene recognition units have been synthesized to promote self‐assemblies similar in appearance to shuttlecocks nested into each other thanks to the conical host cavity created around the fullerene together with the π–π and electronic interactions.     

tBuP(NH2)2--a reactive synthon for the synthesis of molecular imidophosphinates of group 13 metals

Reactions of tBuP(NH(2))(2) with Group 13 trialkyls MR(3) (M=Al, Ga, In; R=Me, tBu) were investigated in detail. According to variable-temperature (VT) NMR investigations, the reaction proceeds stepwise with the initial formation of aminophosphane adducts, which subsequently react to give iminophosphorane adducts and finally the heterocyclic metallonitridophosphinates. BP86/TZVPP (DFT) calculations were performed to verify this reaction pathway, to elucidate the influence of the central Group 13 element on the stability of the reaction intermediates and the heterocycles, as well as to assess the thermodynamics of their formation. The relative stability of free and complexed aminophosphane RP(NH(2))(2) and iminophosphorane R(H(2)N)(H)P=NH (adducts) with P(III) and P(V) centers was studied in more detail with DFT and MP2 methods. In addition, the influence of the substituent R was investigated by variation of R from H to Me, tBu, F, and NH(2). In general, the aminophosphane form was found to be favored for the free ligand, however, upon complexation with MR(3) (M=Al, Ga; R=alkyl) both forms are almost equal in energy.     

Selective rearrangements of quadruply hydrogen-bonded dimer driven by donor-acceptor interaction

A general method has been developed to control the selective rearrangement of Meijer's AADD quadruply hydrogen-bonded homodimers by introducing an additional donor-acceptor interaction. Therefore, one donor-assembling monomer, 1, in which the electron-rich bis(p-phenylene)-34-crown-10 moiety is connected to the hydrogen-bonding moiety, and two acceptor-assembling monomers, 2 and 3, in which the electron-deficient pyromellitic diimide or naphthalene diimide group is incorporated, respectively, are synthesized and characterized. 1H NMR and 2D-NOESY studies show that all these compounds exist as stable homodimers in chloroform. Mixing 1 equiv of 1 with 1 equiv of 2 in chloroform leads to the formation of heterodimers 1.2 in approximately 60 % yield, as a result of the electrostatic interaction between the bis(p-phenylene)-34-crown-10 moiety of 1 and the pyromellitic diimide group of 2. Selective formation of heterodimer 1.3 (>97 %) was achieved by mixing 1 equiv of 1 with 1 equiv of 3 in chloroform which resulted in a strengthened electrostatic interaction between the bis(p-phenylene)-[34]crown-10 moiety of 1 and the naphthalene diimide group of 3. The structures of heterodimers 1.2 and 1.3, which have been characterized by 1H NMR and UV/Vis experiments, reveal a remarkable promoting effect between the donor-acceptor interaction and intermolecular hydrogen-bonding. 1H NMR studies also reveal that heterodimers 1.2 and 1.3 can be fully and partially dissociated by addition of heterocycle 29, leading to the formation of new more robust heterodimers 1.29 and 2.29, or 3.29,respectively, and partially regenerated by subsequent addition of heterocyclic compound 30 through the formation of a new heterodimer 29.30. Heterodimers 1.2 and 1.3 represent a novel class of pseudo[2]rotaxanes constructed by two different noncovalent interactions.     

Synthesis and applications of cyano‐vinylene‐based polymers containing cyclopentadithiophene and dithienosilole units for photovoltaic cells

Two β‐cyano‐thiophenevinylene‐based polymers containing cyclopentadithiophene ( CPDT‐CN ) and dithienosilole ( DTS‐CN ) units were synthesized via Stille coupling reaction with Pd(PPh₃)₄ as a catalyst. The effects of the bridged atoms (C and Si) and cyano‐vinylene groups on their thermal, optical, electrochemical, charge transporting, and photovoltaic properties were investigated. Both polymers possessed the highest occupied molecular orbital (HOMO) levels of about ?5.30 eV and the lowest unoccupied molecular orbital (LUMO) levels of about ?3.60 eV, and covered broad absorption ranges with narrow optical band gaps (ca. 1.6 eV). The bulk heterojunction polymer solar cell (PSC) devices containing an active layer of electron‐donor polymers ( CPDT‐CN and DTS‐CN ) blended with an electron‐acceptor, that is, [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) or [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM), in different weight ratios were explored under 100 mW/cm² of AM 1.5 white‐light illumination. The PSC device based on DTS‐CN: PC₇₁BM (1:2 w/w) exhibited a best power conversion efficiency (PCE) value of 2.25% with V_oc = 0.74 V, J_sc = 8.39 mA/cm², and FF = 0.36. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Syntheses and optoelectronic properties of quinoxaline polymers: The effect of donor unit

Tuning the bandgap of electrochromic polymers is one of the important research topics in electrochromism. To understand clearly the effect of donor unit in donor–acceptor–donor‐type polymers, 2,3‐bis(4‐tert‐butylphenyl)‐5,8‐di(thiophen‐2‐yl)quinoxaline and 2,3‐bis(4‐tert‐butylphenyl)‐5‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐ 5‐yl)‐8‐(thiophen‐2‐yl)quinoxaline were synthesized and polymerized potentiodynamically. Their electrochemical and spectroelectrochemical studies were performed, and the results were compared with those of poly(2,3‐bis(4‐tert‐butylphenyl)‐5,8‐bis(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)quinoxaline) (Gunbas et al., Adv Mater 2008, 20, 691–695). A blue shift in the polymer π–π* transitions revealed that the bandgap of such polymers with the same acceptor unit is related to the electron density of donor units. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Phosphorous disulfide and its ions in the electronic ground state: a gas phase theoretical study

Ab initio molecular orbital theory and density functional theory calculations were performed on the electronic ground states of the open-shell PS₂ molecule and its singly charged ions. A comparison of the optimized molecular structures indicates as the stepwise one-electron reduction of the PS₂⁺ ion, to yield PS₂ and PS₂⁻, provokes a symmetric elongation of both PS bonds along with a bending of its linear equilibrium geometry. The ionization potential (IP), adiabatic electron affinity (EA_ad), and atomization energy (AE) of the open-shell PS₂ molecule were calculated at different levels of theory. The following values were obtained at the more realistic UMP4SDTQ/6-311+G(3df)//UHF/6-311+G(3df) level of theory: IP=8.32 eV, EA_ad=3.03 eV and AE=12.40 eV. At the same level of theory, the calculated vertical detachment energy (VDE) of the PS₂⁻ anion is 3.22 eV. The donor–acceptor complexes formed in the gas-phase upon interaction of either one or two ammonia molecules with PS₂⁺ were also investigated. The calculated gas-phase binding energies indicate that the formation of the bis-adduct is favored over that of the mono-adduct by a binding energy gain of about 20 kcal/mol.     

Ab initio study of long-range electron transfer between biphenyl anion radical and naphthalene

After the separation of the donor, the aeceptor, and the σ-type bridge from the π-σ-π system, the geometries of biphenyl, biphenyl anion radical, naphthalene, and naphthalene anion radical are optimized, and then the reorganization energy for the intermolecular electron transfer (ET) at the levels of HF/4-31G and HF/DZP is calculated. The ET matrix elements of the self-exchange reactions of the π-σ-π systems have been calculated by means of both the direct calculation based on the variational principle, and the transition energy between the molecular orbitals at the linear coordinate R=0.5. For the cross reactions, the ET matrix element and the geometry of the transition state are determined by searching the minimum energy splitting △_(min) along the reaction coordinate. In the evaluation of the solvent reorganization energy of the ET in solution, the Marcus' two-sphere model has been invoked. A few of ET rate constants for the intramolecular ET reactions for the π-σ-π systems, which contain     

Transfer of electron density as a result of hydrogen bond formation

It has been found that the amount of charge transfer between donor and acceptor molecules in four sets of hydrogen‐bonded complexes may be adequately described as an exponential function of the equilibrium distance between the hydrogen atom and the nearest atom of the acceptor molecule. The exponential factors of the transfer are of the same order but somewhat larger than the factors found otherwise in the investigations of dynamic electron transfer. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009