10495-73-5Relevant articles and documents
Syntheses of new binucleating heterocyclic ligands
Slater, Jonathan W.,Steel, Peter J.
, p. 6941 - 6943 (2006)
The syntheses of five new mixed azine-azole binucleating ligands are described.
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Case
, p. 2398 (1966)
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Structure–Activity and Stability Relationships for Cobalt Polypyridyl-Based Hydrogen-Evolving Catalysts in Water
Schnidrig, Stephan,Bachmann, Cyril,Müller, Peter,Weder, Nicola,Spingler, Bernhard,Joliat-Wick, Evelyne,Mosberger, Mathias,Windisch, Johannes,Alberto, Roger,Probst, Benjamin
, p. 4570 - 4580 (2017)
A series of eight new and three known cobalt polypyridyl-based hydrogen-evolving catalysts (HECs) with distinct electronic and structural differences are benchmarked in photocatalytic runs in water. Methylene-bridged bis-bipyridyl is the preferred scaffold, both in terms of stability and rate. For a cobalt complex of the tetradentate methanol-bridged bispyridyl–bipyridyl complex [CoIIBr(tpy)]Br, a detailed mechanistic picture is obtained by combining electrochemistry, spectroscopy, and photocatalysis. In the acidic branch, a proton-coupled electron transfer, assigned to formation of CoIII?H, is found upon reduction of CoII, in line with a pKa(CoIII?H) of approximately 7.25. Subsequent reduction (?0.94 V vs. NHE) and protonation close the catalytic cycle. Methoxy substitution on the bipyridyl scaffold results in the expected cathodic shift of the reduction, but fails to change the pKa(CoIII?H). An analysis of the outcome of the benchmarking in view of this postulated mechanism is given along with an outlook for design criteria for new generations of catalysts.
Rhodium(iii)-catalyzed switchable C-H acylmethylation and annulation of 2,2′-bipyridine derivatives with sulfoxonium ylides
Chen, Chen,Chen, Mengjia,Meng, Haifang,Wang, Yani,Yang, Fang,Zhu, Bolin
, p. 4268 - 4271 (2021)
A novel protocol for Rh(iii)-catalyzed switchable C-H acylmethylation and annulation of 2,2′-bipyridine derivatives with sulfoxonium ylides is reported. This protocol provides a facile approach to synthesize structurally diverse acylmethylated 2,2′-bipyridine derivatives and acyl pyrido[2,3-a]indolizines with a broad range of functional group tolerance.
Synthesis, structural characterization, photophysics, and broadband nonlinear absorption of a platinum(II) complex with the 6-(7-benzothiazol- 2′-yl-9,9-diethyl-9-H-fluoren-2-yl)-2,2′-bipyridinyl ligand
Zhang, Bingguang,Li, Yunjing,Liu, Rui,Pritchett, Timothy M.,Azenkeng, Alexander,Ugrinov, Angel,Haley, Joy E.,Li, Zhongjing,Hoffmann, Mark R.,Sun, Wenfang
, p. 4593 - 4606 (2012)
A platinum complex with the 6-(7-benzothiazol-2′-yl-9,9-diethyl-9H- fluoren-2-yl)-2,2′-bipyridinyl ligand (1) was synthesized and the crystal structure was determined. UV/Vis absorption, emission, and transient difference absorption of 1 were systematically investigated. DFT calculations were carried out on 1 to characterize the electronic ground state and aid in the understanding of the nature of low-lying excited electronic states. Complex 1 exhibits intense structured 1π-π* absorption at λabs1MLCT/ 1LLCT transition at 440-520 nm in CH2Cl2 solution. A structured 3π-π*/3MLCT emission at about 590 nm was observed at room temperature and at 77 K. Complex 1 exhibits both singlet and triplet excited-state absorption from 450 nm to 750 nm, which are tentatively attributed to the 1π-π* and 3π-π* excited states of the 6-(7-benzothiazol-2′- yl-9,9-diethyl-9H-fluoren-2-yl)-2,2′-bipyridine ligand, respectively. Z-scan experiments were conducted by using ns and ps pulses at 532 nm, and ps pulses at a variety of visible and near-IR wavelengths. The experimental data were fitted by a five-level model by using the excited-state parameters obtained from the photophysical study to deduce the effective singlet and triplet excited-state absorption cross sections in the visible spectral region and the effective two-photon absorption cross sections in the near-IR region. Our results demonstrate that 1 possesses large ratios of excited-state absorption cross sections relative to that of the ground-state in the visible spectral region; this results in a remarkable degree of reverse saturable absorption from 1 in CH2Cl2 solution illuminated by ns laser pulses at 532 nm. The two-photon absorption cross sections in the near-IR region for 1 are among the largest values reported for platinum complexes. Therefore, 1 is an excellent, broadband, nonlinear absorbing material that exhibits strong reverse saturable absorption in the visible spectral region and large two-photon-assisted excited-state absorption in the near-IR region.
A polyaromatic terdentate binding unit with fused 5,6-membered chelates for complexing s-, p-, d-, and f-block cations
Hoang, Thi Nhu Y.,Humbert-Droz, Marie,Dutronc, Thibault,Guenee, Laure,Besnard, Celine,Piguet, Claude
, p. 5570 - 5580 (2013)
The polyaromatic terdentate ligand 6-(azaindol-1-yl)-2,2′-bipyridine (L7) combines one 5-membered chelate ring with a fused 6-membered chelate ring. It is designed to provide complexation properties intermediate between 2,2′;6′,2″-terpyridine (L1) (two fused 5-membered chelate rings) and 2,6-bis(azaindol-1-yl)pyridine (L6) (two fused 6-membered chelate rings). In polar organic solvents, L7 displays remarkable affinities for the successive fixation of two small univalent cations M = H+ or Li +, leading to stable [Mm(L7)]m+ (m = 1-2) complexes. Upon reaction with M = Mg2+ or Zn2+ cations, the large positive charge densities borne by the metals result in the successive cooperative complexation of two ligands to give [M(L7)n] n+ (n = 1-2). For small Sc3+, unavoidable traces of water favor the formation of the protonated ligand at millimolar concentrations in acetonitrile, but the use of larger Y3+ cations leads to [Y(L7) n]n+ (n = 1, 2), for which stability constants of log(β1,1Y,L7) = 2.9(5) and log(β1,2Y,L7) = 5.3(4) are estimated. The complexation behaviors are supported by speciations in solution, thermodynamic analyses, and solution and solid-state structures.
Synthesis of Pyridylsulfonium Salts and Their Application in the Formation of Functionalized Bipyridines
Duong, Vincent K.,Horan, Alexandra M.,McGarrigle, Eoghan M.
, p. 8451 - 8457 (2020/11/12)
An S-selective arylation of pyridylsulfides with good functional group tolerance was developed. To demonstrate synthetic utility, the resulting pyridylsulfonium salts were used in a scalable transition-metal-free coupling protocol, yielding functionalized bipyridines with extensive functional group tolerance. This modular methodology permits selective introduction of functional groups from commercially available pyridyl halides, furnishing symmetrical and unsymmetrical 2,2′- A nd 2,3′-bipyridines. Iterative application of the methodology enabled the synthesis of a functionalized terpyridine with three different pyridine components.
Observation of an inversion in photophysical tuning in a systematic study of luminescent triazole-based osmium(II) complexes
Scattergood, Paul A.,Roberts, James,Omar, Salem A.E.,Elliott, Paul I.P.
, p. 8607 - 8621 (2019/08/21)
In a systematic survey of luminescent bis(terdentate) osmium(II) complexes, a tipping point involving a reversal in photophysical tuning is observed whereby increasing stabilization of the ligand-based lowest unoccupied molecular orbital (LUMO) results in a blue shift in the optical absorption and emission bands. The complexes [Os(N^N′^N″)2]2+ [N^N′^N″ = 2,6-bis(1-phenyl-1,2,3-triazol-4-yl)pyridine (Os1), 2,6-bis(1-benzyl-1,2,3-triazol-4-yl)pyrazine (Os2), 6-(1-benzyl-1,2,3-triazol-4-yl)-2,2′-bipyridyl (Os3), 2-(pyrid-2-yl)-6-(1-benzyl-1,2,3-triazol-4-yl)pyrazine (Os4), 2-(pyrazin-2-yl)-6-(1-benzyl-1,2,3-triazol-4-yl)pyridine (Os5), and 6-(1-benzyl-1,2,3-triazol-4-yl)-2,2′-bipyrazinyl (Os6)] have been prepared and characterized, and all complexes display phosphorescence ranging from the orange to near-IR regions of the spectrum. Replacement of the central pyridine in the ligands of Os1 by the more π-accepting pyrazine in Os2 results in a 55 nm red shift in the triplet metal-to-ligand charge-transfer-based emission band, while a larger red shift of 107 nm is observed for the replacement of one of the triazole donors in the ligands of Os1 by a second pyridine ring in Os3 (λemmax = 702 nm). Interestingly, replacement of the central pyridine ring in the ligands of Os3 by pyrazine (Os4, λemmax = 702 nm) fails to result in a further red shift in the emission band. Reversal of the relative positions of the pyridine and pyrazine donors in Os5 (λemmax = 733 nm) compared to Os4 does indeed result in the expected red shift in the emission with respect to that for Os3 based on the increased π-acceptor character of the ligands present. However, an inversion in emission tuning is observed for Os6, in which the incorporation of a second pyrazine donor in the ligand architecture results in a blue shift in the optical absorption and emission maxima (λemmax = 710 nm). Electrochemical studies reveal that while incorporating pyrazine in the ligands indeed results in an expected anodic shift in the first reduction potential through stabilization of the ligand-based LUMO, there is also a concomitant anodic shift in the OsII/OsIII-based oxidation potential. This stabilization of the metal-based highest occupied molecular orbital (HOMO) thus nullifies the effect of stabilization of the LUMO in Os4 compared to Os3, resulting in these complexes having coincident emission maxima. For Os6, stabilization of the HOMO through the incorporation of two pyrazine donors in the ligand structure now exceeds stabilization of the LUMO, resulting in a larger HOMO?LUMO gap and a counterintuitive blue shift in the optical properties in comparison with those of Os5. While it is known that the replacement of ligands (e.g., replacing bipyridyl with bipyrazinyl) can result in a larger HOMO?LUMO energy gap through greater stabilization of the HOMO, these results importantly allow us to capture the tipping point at which this inversion in photophysical tuning occurs. This therefore enables us to explore the limits available in emission tuning with a relatively simple and minimalist ligand structure.
