136538-84-6Relevant articles and documents
Cytotoxicity of cyclometalated platinum complexes based on tridentate NCN and CNN-coordinating ligands: Remarkable coordination dependence
Vezzu, Dileep A.K.,Lu, Qun,Chen, Yan-Hua,Huo, Shouquan
, p. 49 - 56 (2014)
A series of cyclometalated platinum complexes with diverse coordination patterns and geometries were screened for their anticancer activity. It was discovered that the N^C^N-coordinated platinum complex based on 1,3-di(pyridyl)benzene displayed much higher cytotoxicity against human lung cancer cells NCI-H522, HCC827, and NCI-H1299, and human prostate cancer cell RV1 than cisplatin. In a sharp contrast, the C^N^N-coordinated platinum complex based on 6-phenyl-2,2′-bipyridine was ineffective on these cancer cells. This remarkable difference in cytotoxicity displayed by N^C^N- and C^N^N-coordinated platinum complexes was related to the trans effect of the carbon donor in the cyclometalated platinum complexes, which played a crucial role in facilitating the dissociation of the chloride ligand to create an active binding site. The DNA binding was studied for the N^C^N-coordinated platinum complex using electrophoresis and emission titration. The cellular uptake observed by fluorescent microscope showed that the complex is largely concentrated in the cytoplasm. The possible pathways for the cell apoptosis were studied by western blot analysis and the activation of PARP via caspase 7 was observed.
Aromatic interactions in the synthesis and conformation of two collapsible tetracationic cyclophanes
Sindkhedkar, Milind D,Mulla, Hormuzd R,Wurth, Mark A,Cammers-Goodwin, Arthur
, p. 2991 - 2996 (2001)
The conformations of tetracationic paracyclophane and metacyclophane derivatives containing quaternary salts of para-2,2-diazaterphenyl were investigated. The molecules were synthesized as the bromide and hexafluorophosphate salts which allowed solubility in aqueous and organic solvents. Molecular mechanics led to the notion that these cyclophanes would populate collapsed and open conformations in water and only populate open conformers in organic solvent. VT NMR studies indicated that the open and the collapsed conformers did not exchange on the NMR timescale. Large, positively charged clefts in one of these conformers bound flat anions between pyridinium rings as would molecular-scale tweezers.
Luminescent properties of a 3,5-diphenylpyrazole bridged Pt(ii) dimer
Cinninger, Leander M.,Bastatas, Lyndon D.,Shen, Yulong,Holliday, Bradley J.,Slinker, Jason D.
, p. 9684 - 9691 (2019)
We report the synthesis, electrochemistry, photophysical properties and electroluminescence of a highly luminescent pyrazolate-bridged platinum(ii) complex. The complex has the general formula of [((N^C^N)Pt)2(μ-pz)][PF6] where N^C^N = 1,3-di(2-pyridyl)benzene and μ-pz = 3,5-diphenylpyrazolate. The X-ray structure shows that the bridging pyrazolate ligand causes a close Pt-Pt interaction of 3.05(7) ?. The emission profile of the complex was determined in solution, glassy 2-methyltetrahydrofurane at 77 K, and the solid state at both room temperature and 77 K. Each emission profile displayed a strong red metal-metal-to-ligand charge transfer while the solution and glassy 2-methyltetrahydrofurane emission profiles also displayed a ligand-centred transition. The absolute quantum yields of the complex in solution and the solid state at room temperate are 86% and 39%, respectively. Light-emitting electrochemical cells (LEECs) of [((N^C^N)Pt)2(μ-pz)][PF6] were fabricated which displayed appreciable electroluminescence, among the brightest and most efficient LEECs from dinuclear compounds to date.
Terminal redox-site effect on the long-range electron conduction of Fe(tpy)2 oligomer wires on a gold electrode
Katagiri, Shunsuke,Sakamoto, Ryota,Maeda, Hiroaki,Nishimori, Yoshihiko,Kurita, Tomochika,Nishihara, Hiroshi
, p. 5088 - 5096 (2013)
This article completes our comprehensive understanding of the electron transport properties of our original p-conjugated redox-active molecular wires comprising Fe bridged by p-phenylene linkers (tpy=2,2':6',2''-terpyridine). The Fe(tpy)2 oligomer wires comprise three types of tpy ligands: the anchor tpy ligand (A series) makes a junction between the wire and electrode, the bridging bis-tpy ligand (L series) connects the Fe(tpy)2 units, and the terminal tpy ligand (T series) possesses a redox site as a probe for the long-range electron transport ability. Taking advantage of the precise tunability of the composition of the Fe- (tpy)2 oligomer wires, thus far we investigated how A and L impacted on the electron-transport ability. The excellent long-range electron transport ability with ultrasmall attenuation constants (bd, 0.002 -1 as the minimum) depends on L significantly [Chem. Asian J. 2009, 4, 1361], whereas A is unrelated to the bd value, but influences the zero-distance electron-transfer rate constant, ket 0 [J. Am. Chem. Soc.2010, 132, 4524]. Herein we study the influence of terminal ligand Tx (x=1- 3). bd is independent of T, however, T3, with a cyclometallated Ru complex as the redox site, gives rise to a ket 0 value greater than T1 and T2 with ferrocene. This series of simple but definitive conclusions indicates that we have reached the stage of being able to precisely design molecular wires to attain desirable single-molecule electron conduction.
An alcohol soluble amino-functionalized organoplatinum(ii) complex as the cathode interlayer for highly efficient polymer solar cells
Liu, Shengjian,Zhang, Guichuan,Lu, Junming,Jia, Jianchao,Li, Wei,Huang, Fei,Cao, Yong
, p. 4372 - 4379 (2015)
A small-molecule amino-functionalized organoplatinum(ii) complex Pt-N has been developed. The unique properties of Pt-N, including a well-defined chemical structure, an excellent solubility in environmentally friendly polar solvents and good electron extraction to high work-function metals, make it a promising candidate for cathode interfacial modification of solution processed multilayer polymer solar cells (PSCs). The resultant PSCs with an ITO/PEDOT:PSS/PTB7:PC71BM/interlayer/Al device configuration exhibited significantly improved efficiencies from 3.62% for an unmodified device to 8.89% by using a Pt-N cathode interlayer, benefiting from the dramatic enhancement in the open circuit voltage (0.53 V for bare Al PSCs to 0.75 V for Pt-N/Al PSCs), the fill factor (43.58% for bare Al PSC to 72.49% for Pt-N/Al PSC), and a slight increase in short-circuit current density. These results indicate that Pt-N is a new promising candidate as the cathode interlayer for highly efficient PSCs. This journal is
Cyclometalated Ni(II) Complexes [Ni(NΛCΛN)X] of the Tridentate 2,6-di(2-pyridyl)phen-ide Ligand
Kletsch, Lukas,H?rner, Gerald,Klein, Axel
, p. 2820 - 2829 (2020)
A series of cyclometalated Ni(II) complexes [Ni(PyPhPy)X] containing anionic NΛCΛN- tridentate ligand Py(Ph-)Py 2,6-di(2-pyridyl)benzene-1-ide, (Py(HPh)Py = 1,3-di(2-pyridyl)benzene) and X = Cl, Br, or I as coligands, were studied. All three complexes were obtained through direct C-H base-assisted nickelation from NiX2 and Py(HPh)Py using KOAc/K2CO3 in nonpolar high-boiling point solvents. While the overall molecular structures are quite similar to those of the previously studied [Ni(CΛNΛN)X] complexes with the anionic CΛNΛN tridentate -Phbpy (HPhbpy = 6-(phenyl)-2,2′-bipyridine) ligand, bond lengths in the molecular structures are slightly different. Large differences between these NΛCΛN and CΛNΛN Ni complexes which can be traced to the different orientation of the X coligand to the carbanionic phen-ide group, trans or cis, and the different ligand pattern, Py-Ph-Py versus Ph-Py-Py, were found for the UV-vis absorption spectra and the electrochemical reductions, while the oxidation potentials are very similar. Extended DFT calculations with the TPSSh functional associate the indifference of oxidation potentials with conserved energies of metal-borne HOMOs. By contrast, the diminished π-acceptor qualities of the NΛCΛN ligand translate into a destabilization of the LUMO by ca. 400 mV and a blue-shift of the leading visible transition by 80 nm in very good agreement with the experimental data.
Yttrium-Catalyzed ortho-Selective C?H Borylation of Pyridines with Pinacolborane
Jiang, Shengjie,Luo, Yuncong,Xu, Xin
, (2022/03/31)
This work reports a site-selective C?H borylation of pyridines at the ortho-position with pinacolborane enabled by an yttrocene catalyst. The reaction provides a new family of 2-pyridyl boronates with a broad substrate scope and high atom efficiency. The resultant boronates were able to undergo a variety of transformations, e.g., oxidation, Suzuki–Miyaura coupling, Chan–Lam amination and etherification. Catalytic intermediates, including ortho-C?H metalated and borylated complexes, were isolated from stoichiometric experiments and confirmed by single-crystal X-ray diffraction.
Electronic Properties of Oxidized Cyclometalated Diiridium Complexes: Spin Delocalization Controlled by the Mutual Position of the Iridium Centers
Hu, Yu Xuan,Zhang, Jing,Zhang, Fangfang,Wang, Xiaoyan,Yin, Jun,Hartl, Franti?ek,Liu, Sheng Hua
, p. 4567 - 4575 (2020/03/24)
Four cyclometalated diiridium complexes, with IrCp*Cl (Cp=η5-C5Me5 ?) termini bridged by 1,4- and 1,3-bis(p-tolyliminoethyl)benzene (1, 2), or 1,4- and 1,3-bis(2-pyridyl)benzene (3, 4), were prepared and characterized by nuclear magnetic resonance (NMR) spectroscopy and single-crystal X-ray diffraction (complexes 1, 2, and 4). The two iridium centers in complexes 1 and 3 are thus bound at the central benzene ring in the para-position (trans-Ir2), whereas those in complexes 2 and 4 are in the meta-position (cis-Ir2). Cyclic voltammograms of all four complexes show two consecutive one-electron oxidations. The potential difference between the two anodic steps in 1 and 3 is distinctly larger than that for 2 and 4. The visible–near-infrared (NIR)–short-wave infrared (SWIR) absorption spectra of trans-Ir2 monocations 1+ and 3+ are markedly different from those of cis-Ir2 monocations 2+ and 4+. Notably, strong near-infrared electronic absorption appears only in the spectra of 1+ and 3+ whereas 2+ and 4+ absorb only weakly in the NIR-SWIR region. Combined DFT and TD-DFT calculations have revealed that (a) 1+ and 3+ (the diiridium-benzene trans-isomers) display the highest occupied spin-orbitals (HOSO) and the lowest unoccupied spin-orbital (LUSO) evenly delocalized over both molecule halves, and (b) their electronic absorptions in the NIR-SWIR region are attributed to mixed metal-to-ligand and ligand-to-ligand charge transfers (MLCT and LLCT). In contrast, cis-isomers 2+ and 4+ do not feature this stabilizing π-delocalization but a localized mixed-valence state showing a weak intervalence charge-transfer (IVCT) absorption in the SWIR region.
Synthesis and self-assembly of NCN-pincer Pd-complex-bound norvalines
Ogata, Kazuki,Sasano, Daisuke,Yokoi, Tomoya,Isozaki, Katsuhiro,Yoshida, Ryota,Takenaka, Toshio,Seike, Hirofumi,Ogawa, Tetsuya,Kurata, Hiroki,Yasuda, Nobuhiro,Takaya, Hikaru,Nakamura, Masaharu
, p. 12356 - 12375 (2013/09/23)
The NCN-pincer Pd-complex-bound norvalines Boc-D/L-[PdCl(dpb)]Nva-OMe (1) were synthesized in multigram quantities. The molecular structure and absolute configuration of 1 were unequivocally determined by single-crystal X-ray structure analysis. The robustness of 1 under acidic/basic conditions provides a wide range of N-/C-terminus convertibility based on the related synthetic transformations. Installation of a variety of functional groups into the N-/C-terminus of 1 was readily carried out through N-Boc- or C-methyl ester deprotection and subsequent condensations with carboxylic acids, R 1COOH, or amines, R2NH2, to give the corresponding N-/C-functionalized norvalines R1-D/L-[PdCl(dpb)]Nva- R2 2-9. The dipeptide bearing two Pd units 10 was successfully synthesized through the condensation of C-free 1 with N-free 1. The robustness of these Pd-bound norvalines was adequately demonstrated by the preservation of the optical purity and Pd unit during the synthetic transformations. The lipophilic Pd-bound norvalines L-2, Boc-L-[PdCl(dpb)]Nva-NH-n-C 11H23, and L-4, n-C4H9CO-L- [PdCl(dpb)]Nva-NH-n-C11H23, self-assembled in aromatic solvents to afford supramolecular gels. The assembled structures in a thermodynamically stable single crystal of L-2 and kinetically stable supramolecular aggregates of L-2 were precisely elucidated by cryo-TEM, WAX, SAXS, UV/Vis, IR analyses, and single-crystal X-ray crystallography. An antiparallel β-sheet-type aggregate consisting of an infinite one-dimensional hydrogen-bonding network of amide groups and π-stacking of PdCl(dpb) moieties was observed in the supramolecular gel fiber of L-2, even though discrete dimers are assembled through hydrogen bonding in the thermodynamically stable single crystal of L-2. The disparate DSC profiles of the single crystal and xerogel of L-2 indicate different thermodynamics of the molecular assembly process. Metalated amino acids: A series of NCN-pincer Pd-complex-bound norvaline derivatives was successfully synthesized without loss of the optical purity and Pd unit. Efficient self-assembly properties of these Pd-norvalines were found to afford well-regulated Pd arrays both in the single crystal and in the supramolecular gel. A solvent-dependent configuration control of the Pd array was corroborated by means of single-crystal X-ray crystallography and cryo-TEM analysis. Copyright
Single-flask preparation of polyazatriaryl ligands by sequential borylation/Suzuki-Miyaura coupling
Avitia, Bertoldo,MacIntosh, Eric,Muhia, Samuel,Kelson, Eric
supporting information; experimental part, p. 1631 - 1634 (2011/05/05)
We report a convenient single-flask methodology for the preparation of polyazatriaryl products with relevance to luminescence, catalysis, and pharmacology. The diborylation of 1,3-dibromobenzenes and double Suzuki-Miyaura coupling produces 1,3-diheteroarylbenzenes. Similarly, borylation of heteroaryl halides and double coupling to 2,6-dichloropyridine produces 2,6-diheteroarylpyridines. This methodology appears general in producing challenging polyheteroaryl targets as long as the boronic esters have no ortho heteroatoms and coupling avoids adjacent oxygens.
