DFT study of the electronic and charge transfer properties of perfluoroarene–thiophene oligomers

The ground state structures of 5,5″-diperfluorophenyl-2,2′:5′,2″:5″,2‴-quaterthiophene (1), 5,5′-bis{1-[4-(thien-2-yl)perfluorophenyl]}-2,2′-dithiophene (2), 4,4′-bis[5-(2,2′-dithiophenyl)]-perfluorobiphenyl (3), 5,5″-diperfluorophenyl-2,2′:5′,2″-tertthiophene (4), 5,5′-diperfluorophenyl-2,2′-dihiophene (5), and 5,5-diperfluorophenylthiophene (6) have been optimized at the B3LYP/6-31G(d), B3LYP/6-31G(d,p), PBE0/6-31G(d), and PBE0/6-31G(d,p) level of theories. The B3LYP/6-31+G(d) and PBE0/6-31+G(d) level of theories have been applied to investigate the absorption spectra. The PBE0 functional is good to predict the C–S bond lengths while the C–F bond lengths are good envisaged with B3LYP functional. The increment of thiophene rings between two perfluoroarene rings leads to red shift in absorption spectra. The electron affinities are energetically destabilized while energetic stabilization of the radical-cation increases by decreasing the thiophene rings from four to one. The perfluoroarene rings leads to enhance the electron injection.     

Terpyridines as supramolecular initiators for living polymerization methods

Bis(5,5″-bis(bromomethyl)-2,2′:6′,2″-terpyridine), bis-4′-(4-bromomethylphenyl)-2,2′:6′,2″-terpyridine and 4-hydroxymethyl-5′,5″-dimethyl-2,2′:6′,2″-terpyridine metal complexes have been used as initiators for the living polymerization of 2-oxazolines and L-lactides. In both cases polymers with controlled molecular weights and narrow molecular weight distributions have been obtained. In-line diode array GPC measurements of iron(II) complexed poly(ethyloxazoline)s showed an unexpected absence of fragmentation. Viscosity experiments demonstrated the differences of the complexed and uncomplexed systems.     

Synthesis,magnetic properties and theoretical calculations of novel nitronyl nitroxide and imino nitroxide diradicals grafted on terpyridine moiety

The synthetic route based on Stille coupling between tributyltinpyridyl derivatives and bromo substituted mono- and dipyridyl-carbaldehyde is used for the synthesis of 5,5″-diformyl-2,2′:6′,2″-terpyridine (8). A sequence of Ullman coupling with 2,3-bis(hydroxylamino)-2,3-dimethylbutane followed by oxidation under phase transfer conditions affords either 5,5″-Bis(1-oxyl-3-oxo-4,4,5,5-tetramethylimidazolidin-2-yl)2,2′:6′,2″-terpyridine (10) (diNN-Terpy) or the related 5,5″-Bis(1-oxyl-4,4,5,5-tetramethylimidazolidin-2-yl)2,2′:6′,2″-terpyridine (11) (diIN-Terpy), where both biradicals display clear intramolecular ferromagnetic interaction between the single spin units as evidenced by ESR spectroscopy. Quantum chemical calculations (ROHF/AM1) are performed showing the triplet ground-state for both 10 and 11 radicals.     

Transient Raman detection of excited state electron,transfer to methyl viologen from photoexcited molecular reagents in fluid solution and anchored to SiO2

The lowest electronic excited state of the complexes [Ru(2,2′-bipyridine)₃]²⁺, fac-[ClRe (CO)₃(2,2′-bipyridine)], and fac-[(pyridine) Re (CO)₃(2,2′-bipyridine)]⁺ can be quenched by methyl viologen, MV²⁺, N,N′-dimethyl-4,4′-bipyridinium, in fluid solutions. The quenching obeys Stern—Volmer kinetics as deduced from plots of relative luminescence quantum yield vs [MV²⁺], and the data are consistent with a quenching process that is essentially diffusion controlled. Pulsed laser excitation (18 ns, 354.7 nm frequency tripled Nd: YAG) of the metal complexes in the presence of MV²⁺ shows that a detectable fraction of the quenching results in net electron transfer to form MV⁺. The MV⁺ is detectable by resonance Raman scattering from the trailing portion of the excitation pulse. Excited state electron transfer to MV²⁺ from a photo-excited complex anchored to SiO₂ has also been detected by transient Raman spectroscopy. High surface area SiO₂ was functionalized by reaction with 4-[2-(trimethoxysilyl)ethyl]pyridine to give [SiO₂]-SiEtpyr. Reaction of [SiO₂]-SiEtpyr with [(CH₃CN)Re(CO)₃(2,2′-bipyridine)]⁺ then yields [SiO₂]-[(SiEtpyr) Re (CO)₃ (2,2′-bipyridine)]⁺. Electron transfer quenching of the photo-excited immobilized Re complex occurs when suspended in CH₃CN solutions of MV²⁺ to yield MV⁺ as detected by resonance Raman scattering and by lifetime attenuation in the presence of MV²⁺.     

Tris(2,2′‐bipyridine)ruthenium Derivatives with Multiple Viologen Acceptors: Quadratic Dependence of Photocatalytic H2 Evolution Rate on the Local Concentration of the Acceptor Site

Three Ru(bpy)₃²⁺ derivatives tethered to multiple viologen acceptors, [Ru(bpy)₂(4,4′‐MV2)]⁶⁺, [Ru(bpy)₂(4,4′‐MV4)]¹⁰⁺, and [Ru(bpy)(4,4′‐MV4)₂]¹⁸⁺ [bpy=2,2′‐bipyridine, 4,4′‐MV2=4‐ethoxycarbonyl‐4′‐(N‐G₁‐carbamoyl)‐2,2′‐bipyridine, and 4,4′‐MV4=4,4′‐bis(N‐G₁‐carbamoyl)‐2,2′‐bipyridine, where G₁=Asp(NHG₂)‐NHG₂ and G₂=‐(CH₂)₂‐N⁺C₅H₄‐C₅H₄N⁺‐CH₃] were prepared as “photo‐charge separators (PCSs)”. Photoirradiation of these complexes in the presence of a sacrificial electron donor (EDTA) results in storage of electrons per PCS values of 1.3, 2.7, and 4.6, respectively. Their applications in the photochemical H₂ evolution from water in the presence of a colloidal Pt H₂‐evolving catalyst were investigated, and are discussed along with those reported for [Ru(bpy)₂(5,5′‐MV4)]¹⁰⁺, [Ru(4,4′‐MV4)₃]²⁶⁺, and [Ru(5,5′‐MV4)₃]²⁶⁺ (Inorg. Chem. Front. 2016 , 3, 671–680). The PCSs with high dimerization constants (K_d=10⁵–10⁶ m ^?1) are superior in driving H₂ evolution at pH 5.0, whereas those with lower K_d values (10³–10⁴ m ^?1) are superior at pH 7.0, where K_d=[(MV⁺)₂]/[MV^{+ .} ]². The (MV⁺)₂ site can drive H₂ evolution only at pH 5.0 as a result of its 0.15 eV lower driving force for H₂ evolution relative to MV^{+ .} , whereas the PCSs with lower K_d values exhibit higher performance at pH 7.0 owing to the higher population of free MV^{+ .} . Importantly, the rate of electron charging over the PCSs is linear to the apparent H₂ evolution rate, and shows an intriguing quadratic dependence on the number of MV²⁺ units per PCS.     

Synthesis and characterization of new copolymers of thiophene and vinylene: Poly(thienylenevinylene)s and poly(terthienylenevinylene)s with thioether side chains

Poly[3,4-bis(3-methylbutylthio)thienylenevinylene], poly[3,4-bis-(S)-(2-methylbutylthio)thienylenevinylene], poly[3′,4′-bis(3-methylbutylthio)-2,2′:5′,2″-terthienylene-5,5″-vinylene], and poly{3′,4′-bis-(S)-[2-methylbutylthio]-2,2′:5′,2″-terthienylene-5,5″-vinylene} have been synthesized. The synthesis starts from the thiophene monomers and trimers, which are formylated to give the corresponding dialdehydes. The dialdehydes are reductively polymerized using a McMurry coupling. The polymers are characterized by GPC, optical spectroscopy (FT-IR, UV-vis, circular dichroism spectroscopy and photoluminescence) and by proton and carbon NMR spectroscopy. The polymers are soluble in common organic solvents, such as THF, chloroform, toluene, benzene and 1,2-dichlorobenzene. The solvatochromism and thermochromism of the polymers in solution are investigated, while the optical activity of the polymers is used to investigate the supramolecular aggregation. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4629–4639, 1999     

Synthesis and Mesogenic Properties of Novel Terthiophene Derivatives

To develop novel oligothiophene‐based liquid crystals involving hydrogen bonding, new terthiophene derivatives containing a stearylamide group, N,N′‐distearyl‐5,5″‐dicyano‐2,2′∶5′,2″‐terthiophene‐4,4″‐dicarboxamide (DNC₁₈DCN 3T) and N,N′‐distearyl‐5,5′‐dipropyl‐2,2′∶5′,2′‐terthiophene‐4,4″‐dicarboxamide (DNC₁₈ DP3T), were designed and synthesized, and their thermal behavior examined. Although DNC₁₈DP3T did not exhibit liquid crystallinity, DNC₁₈DCN3T was found to form smectic A phase.     

Chromium(VI) oxide-mediated oxidation of polyalkyl-polypyridines to polypyridine-polycarboxylic acids with periodic acid

4,4′-Dicarboxy-2,2′-bipyridine was synthesized quantitatively by chromium(VI) oxide-mediated oxidation of 4,4′-dimethyl-2,2′-bipyridine or 4,4′-diethyl-2,2′-bipyridine with periodic acid as the terminal oxidant in sulfuric acid. 5,5′-Dicarboxy-2,2′-bipyridine and 6,6’-dicarboxy-2,2′-bipyridine were also synthesized by the method from the corresponding dimethyl bipyridines in excellent yields. 4,4′,4″-Tricarboxy-2,2′:6′,2″-terpyridine was obtained in 80% yield from 4,4′,4″-triethyl-2,2′:6′,2″-terpyridine, and 4,4′,4″,4′″-tetracarboxy-2,2′:6′,2″:6″,2′″-quaterpyridine was obtained in 72% yield from 4,4′,4″,4′″-tetraethyl-2,2′:6′,2″:6″,2′″-quaterpyridine by the same procedure.     

Reactions of 2,2′,5′,2′-terfuran

Formylation of 2,2′,5′,2′-terfuran ( 1 ) with N-methylformanilide and phosphorus oxychloride gave 5-formyl-2,2′,5′,2′-terfuran ( 2 ) and 5,5′-diformyl-2,2′5′,2′-terfuran ( 3 ). Reduction of 2 and 3 afforded 5-hydroxymethyl-2,2′,5′,2′-terfuran ( 4 ) and 5,5′ dihydroxymethyl-2,2′,5′,2′-terfuran ( 5 ), respectively. Terfuran 1 reacted with phenylmagnesium bromide to give 5-(phenylhydroxymethyl)-2,2′,5′,2′-terfuran ( 6 ), and was carbonated to 5-carboxy 2,2′,5′,2′-terfuran ( 7 ) and 5,5′-dicarboxy-2,2′,5′,2′-terfuran ( 8 ). Bromination of 1 with N-bromosuccinimide gave 5,5′-dibromo 2,2′,5′,2′-terfuran ( 9 ).     

Synthesis,characterization, and evaluation of biological activities of new 4′‐substituted ruthenium (II) terpyridine complexes: Prospective anti‐inflammatory properties

The synthesis and characterization of Ru (II) terpyridine complexes derived from 4′ functionalized 2,2′:6′,2″‐terpyridine (tpy) ligands are reported. The heteroleptic complexes comprise the synthesized ligands 4′‐(2‐thienyl)‐ 2,2′:6′,2″‐terpyridine) or (4′‐(3,4‐dimethoxyphenyl)‐2,2′:6′,2″‐terpyridine and (dimethyl 5‐(pyrimidin‐5‐yl)isophthalate). The new complexes [Ru(4′‐(2‐thienyl)‐2,2′:6′,2″‐terpyridine)(5‐(pyrimidin‐5‐yl)‐isophthalic acid)Cl₂] ( 9 ), [Ru(4′‐(3,4‐dimethoxyphenyl)‐2,2′:6′,2″‐terpyridine)(5‐(pyrimidin‐5‐yl)‐isophthalic acid)Cl₂] ( 10 ), and [Ru(4′‐(2‐thienyl)‐2,2′:6′,2″‐terpyridine)(5‐(pyrimidin‐5‐yl)‐isophthalic acid)(NCS)₂] ( 11 ) were characterized by ¹H‐ and ¹³C‐NMR spectroscopy, C, H, N, and S elemental analysis, UPLC‐ESI‐MS, TGA, FT‐IR, and UV‐Vis spectroscopy. The biological activities of the synthesized ligands and their Ru (II) complexes as anti‐inflammatory, antimicrobial, and anticancer agents were evaluated. Furthermore, the toxicity of the synthesized compounds was studied and compared with the standard drugs, namely, diclofenac potassium and ibuprofen, using hemolysis assay. The results indicated that the ligands and the complex 9 possess superior anti‐inflammatory activities inhibiting albumin denaturation (89.88–100%) compared with the standard drugs (51.5–88.37%) at a concentration of 500 μg g^?1. These activities were related to the presence of the chelating N‐atoms in the ligands and the exchangeable chloro‐ groups in the complex. Moreover, the chloro‐ and thiophene groups in complex 9 produce a higher anticancer activity compared with its isothiocyanate derivative in the complex 11 and the 3,4‐dimethoxyphenyl moiety in complex 10 . Considering the toxicity results, the synthesized ligands are nontoxic or far less toxic compared with the standard drugs and the metal complexes. Therefore, these newly synthesized compounds are promising anti‐inflammatory agents in addition to their moderate unique broad antimicrobial activity.     

Efficiency of polymer sensitizer in photosensitized reaction of tris(bipyridine)ruthenium(II) complex-containing polymer

Photochemical properties of Ru(bpy)₂(poly-4-methyl-4′-vinyl-2,2′-bipyridine)Cl₂ ( 2 ) were studied and compared with that of Ru(bpy)₃Cl₂. Continuous irradiation of a solution, which contains polymer 2 as a photosensitizer, methylviologen (MV²⁺) or 4,4′-bipyridinium-1,1′-bis(trimethylenesulfonate) (SPV) as an electron acceptor and triethanolamine (TEOA) as a sacrificial donor, resulted in the formation of viologen radical ion (MV⁺ or SPV^?). The rate of formation of MV⁺ or SPV^? for the polymer 2 system was smaller than that for the Ru(bpy)₃ Cl₂ systems. The reason for this fact was kinetically analyzed by quenching experiments of excited Ru(II) complexes by MV²⁺ or SPV, the photosensitized reactions of the TEOA–Ru(II) complex–MV²⁺ or -SPV systems, and the dye laser photolysis of the Ru(II) complex–MV²⁺ or -SPV systems.     

Engineering with metallo-supramolecular polymers: linear coordination polymers and networks

Here we demonstrate the synthesis of telechelics with different spacer units and different numbers of metal-complexing units, like α-methoxy-ω-(2,2′:6′,2″-terpyrid-4′-yl)-poly(ethylenoxide)₇₈ ( 1 ), bis(2,2′:6′,2″-terpyrid-4′-yl) di(ethylene glycol) ( 2 ), bis(2,2′:6′,2″-terpyrid-4′-yl)-poly(ethylene oxide)₁₈₀ ( 3 ) and tris[(2,2′:6′,2″-terpyrid-4′-yl)-oligo (ethylenoxy-)_3.33]glycerin ( 4 ) utilizing 4-chloro-2,2′:6′,2″-terpyridine. The complexation behaviour of a variety of metal-salts towards the telechelics was studied and different supramolecular architectures were investigated, such as symmetric polymeric complexes and linear coordination polymers. Furthermore, attempts have been undertaken to prepare metallo-supramolecular cross-linked systems.     

Synthesis,processing, and third-order nonlinear optical properties of benzobisthiazole polymers containing thiophene moieties

Benzobisthiazole polymers containing mono-, bi-, and terthiophene moieties were synthesized through polycondensation in polyphosphoric acid of 2,5-diamino-1,4-benzenedithiol dihydrochloride with thiophene-2,5-dicarboxylic acid, 2,2′-bithiophene-5,5′-dicarboxylic acid, and 2,2′:5′,2″-terthlophene-5,5″-dicarboxylic acid, or their corresponding diacid chlorides, respectively. Intrinsic viscosities of up to 8.1 dL/g (methanesulfonic acid, 30°C) were recorded. Polymer structures were verified by elemental analysis and spectroscopic comparison of the polymers with appropriate model compounds. Onset of breakdown under thermogravimetric analysis in air occurred in the 460–590°C range with the benzobisthiazole polymers containing a monothiophene linkage being the most stable. Films suitable for third-order optical susceptibility measurements could be prepared by extrusion techniques from the benzobisthiazole polymer containing a monothiophene linkage. Degenerate four wave mixing measurements on this film yielded a third order optical susceptibility χ⁽³⁾ of approximately 4.5 × 10^?10 esu. © 1993 John Wiley & Sons, Inc.     

Phase transition equilibrium of terthiophene isomers

The thermodynamic study of the phase transition (fusion and sublimation) of 2,2′:5′,2″-terthiophene and 3,2′:5′,3″-terthiophene is presented. The obtained data is used to evaluate the (solid + liquid) and (solid + gas) phase equilibrium, and draw the phase diagrams of the pure compounds near the triple point coordinates. For each compound the vapour pressures at different temperatures were measured by a combined Knudsen effusion method with a vacuum quartz crystal microbalance. Based on the previous results, the standard molar enthalpies, entropies and Gibbs energies of sublimation were derived at T = 298.15 K. For the two terthiophenes and for 3,3′-bithiophene, the temperature, and the molar enthalpies of fusion were measured in a power compensated differential scanning calorimetry. The relationship between structure and energetics is discussed based on the experimental results, ab initio calculations and previous literature data for 2,2′-bithiophene and 3,3′-bithiophene. The 3,2′:5′,3″-terthiophene shows a higher solid phase stability than the 2,2′:5′,2″-terthiophene isomer arising from the higher cohesive energy due to positioning of the sulphur atom in the thiophene ring. The higher phase stability of 3,3′-bithiophene relative to 2,2′-bithiophene isomer is also related to its higher absolute entropy in the solid phase associated with the ring positional degeneracy observed in the crystal structure of this isomer. A significant differentiation in the crystal phase stability between isomers was found.     

An Efficient and Easy Synthesis of Tetrasubstituted 2,2′:6′,2″-Terpyridines

An efficient synthesis of 4,4″-dinitro-5,5″-dimethyl-2,2′:6′,2″-terpyridine was accomplished. The crystal structures of three different 2,2':6’,2″-terpyridines were determined by x-ray analysis.     

Synthesis and Photovoltaic Properties of Formyl End-Capped Oligothiophenes

For the purpose of developing novel photovoltaic materials, 5,5″-biformyl-2,2′:5′,2″-terthiophene (OHC-3T-CHO) and 5,5″″-biformyl-2,2′:5′,2″:5″,2″′:5″′,2″″-q-uinquethiophene (OHC-5T-CHO) were synthesized. The photovoltaic properties of OHC-3T-CHO and OHC-5T-CHO were studied. We have fabricated two flexible organic photovoltaic devices using OHC-3T-CHO, OHC-5T-CHO, and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA). The PET-ITO (indium tin oxides coated with polyethylene terephthalate)/OHC-3T-CHO/PTCDA/Al device has an open circuit voltage (V _oc ) of 1.12 V, and photoelectric conversion efficiency (PCE) of 1.00%, whereas the PET-ITO/OHC-5T-CHO/PTCDA/Al device has a V _oc of 1.78 V and PCE of 1.08%. Both devices have high V _oc (1.12 V and 1.78 V). It is possible that intermolecular hydrogen bonding between the –CHO group of OHC-nT-CHO and the carboxylic dianhydride of PTCDA enhanced the efficiency by promoting forward interfacial electron transfer.     

Synthesis and supramolecular networks of mono- and dinuclear manganese chloride complexes with 2-(2,2′ : 6′,2″-terpyridin-4′-yl)phenol

2-(2,2′?:?6′,2″-Terpyridin-4′-yl)phenol has been prepared with an improved one-pot method. The reaction between the ligand and MnCl₂ in ethanol at ambient or hydrothermal conditions afforded dichlorido[2-(2,2′?:?6′,2″-terpyridin-4′-yl)phenol-κ³ N,N′,N″]manganese(II) and dichloridobis[µ-2-(2,2′?:?6′,2″-terpyridin-4′-yl)phenolate-κ³ N,N′,N″-κO]dimanganese(II), respectively. Face-to-face π–π stacking interactions between the pyridine rings play a crucial role in supramolecular networks of both complexes. Both complexes display weaker photoluminescence than the free ligand and the dinuclear complex luminescence was stronger than the mononuclear one.     

A new method of using supercritical carbon dioxide as a green solvent for synthesis and purification of 5,5‴-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2‴-quaterthiophene,which is one of n-type organic semiconducting materials

We have investigated synthesis as well as purification of 5,5?-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2?-quaterthiophene (BFH-4?T, n-type organic semiconducting material) using supercritical carbon dioxide (scCO₂) as a green solvent. BFH-4T was obtained in good selectivity and high yield by TDAE/PdCl₂-catalyzed reductive coupling reaction of 5-bromo-5′-(tridecafluorohexyl)-2,2′-bithiophene in scCO₂. We have also successfully established purification of the reaction mixture by passing scCO₂ in the reaction vessel. The product was yellow powder of BFH-4T with purity of more than 99% and Pd catalyst was not contained.     

DNA-binding and cleavage activity of polypyridyl ruthenium(II) complexes

Polypyridyl ruthenium(II) complexes [Ru^II(3-bptpy)(dmphen)Cl]ClO₄ (1), [Ru^II(3-cptpy)(dmphen)Cl]ClO₄ (2), [Ru^II(2-tptpy)(dmphen)Cl]ClO₄ (3), and [Ru^II(9-atpy)(dmphen)Cl]ClO₄ (4) {where 3-bptpy?=?4′-(3-bromophenyl)-2,2′:6′,2″-terpyridine, 3-cptpy?=?4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine, 2-tptpy?=?4′-(2-thiophenyl)-2,2′:6′,2″-terpyridine, 9-atpy?=?4′-(9-anthryl)-2,2′:6′,2″-terpyridine, dmphen?=?2,9-dimethyl-1,10-phenanthroline} have been synthesized and characterized. The DNA-binding properties of the complexes with Herring Sperm DNA have been investigated by absorption titration and viscosity measurements. The ability of complexes to break the pUC19 DNA has been checked by gel electrophoresis. The experimental results suggest that all the complexes bind DNA via partial intercalation. The results also show that the order of DNA-binding affinities of the complexes is 4?<?3?<?2?<?1, confirming that planarity of the ligand in a complex is very important for DNA-binding.     

Syntheses of three naturally occurring polybrominated 3,3′-bi-1H-indoles

The naturally occurring polybrominated indoles 2,2′,5,5′-tetrabromo-3,3′-bi-1H-indole, 2,2′,6,6′-tetrabromo-3,3′-bi-1H-indole, and 2,2′,5,5′,6,6′-hexabromo-3,3′-bi-1H-indole were synthesized using a palladium catalyzed, carbon monoxide mediated, double reductive N-heterocyclization of 2,3-bis(2-nitro-4(or 5)-bromophenyl)-1,4-butadienes as the key step.