- Platinum and palladium complexes of tridentate ?C^N^N (phen-ide)-pyridine-thiazol ligands – A case study involving spectroelectrochemistry, photoluminescence spectroscopy and TD-DFT calculations
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Four Pd(II) and Pt(II) complexes [M(C^N^N)Cl] (HC^N^N = 2-(6-phenylpyridin-2-yl)thiazoles) were synthesised, analysed and characterised using 1H NMR and MS in solution, as well as single crystal XRD in the solid. Cyclic voltammetry of the square planar complexes showed reversible or partially reversible reductions and irreversible oxidations. DFT calculations allowed assigning them to essentially metal-centred oxidations and ligand-centred reductions. Absorption spectra of the complexes show intense absorption bands into π-π* states in the UV to visible spectral range and long-wavelength bands which were assigned to transitions into mixed metal-to-ligand charge transfer (MLCT)/π-π* states, based on TD-DFT calculations. Comparison of Pt and Pd derivatives showed that the energy of the (MLCT)/π-π* bands are increased for Pd over Pt. This was also observed for the phosphorescence at 77 K and is attributed to the higher oxidation potential for Pd and supported by spectroelectrochemical measurements. The photoluminescence quantum yield (ΦL) drops drastically from Pt to Pd at room temperature, where only the two Pt(II) complexes are luminescent showing a broad unstructured phosphorescence from a 3MLCT state. At 77 K, the phosphorescence is blue-shifted and shows a clear vibrational progression, which is related to an enhanced ligand-centred character due to the lack of solvent stabilisation in the frozen matrix that otherwise increases the MLCT contribution. The Pd(II) complexes are not emissive at 298 K, but luminesce at 77 K. This is due to metal-centred dissociative d-d* states that facilitate radiationless deactivation, which cannot be thermally populated at low temperatures. Thus, similar ΦL are observed in frozen glassy matrices for both metals. TD-DFT calculations provided insight into the excited states and showed that the substitution pattern does not affect the emission, due to the lack of participation of the phenyl unit in the orbitals that are relevant for the description of the emissive state.
- Krause, Maren,von der Stück, René,Brünink, Dana,Buss, Stefan,Doltsinis, Nikos L.,Strassert, Cristian A.,Klein, Axel
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supporting information
(2021/01/25)
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- Aerobic C(sp2)-H Hydroxylations of 2-Aryloxazolines: Fast Access to Excited-State Intramolecular Proton Transfer (ESIPT)-Based Luminophores
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The direct hydroxylation of 2-aryloxazolines via a deprotonative magnesiation using TMPMgCl·LiCl and subsequent oxidation with molecular oxygen or air as a green oxidant is reported. This method proceeds under mild conditions at room temperature with high regioselectivity and chemoselectivity. The obtained phenols exhibit tunable luminescence properties, induced by excited-state intramolecular proton transfer. This method opens a new opportunity for the sustainable synthesis of luminescent organic molecules.
- G?bel, Dominik,Clamor, Nils,Lork, Enno,Nachtsheim, Boris J.
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supporting information
p. 5373 - 5377
(2019/06/07)
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- An efficient synthesis of porphyrins with different meso substituents that avoids scrambling in aqueous media
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We have developed new conditions that afford regioisomerically pure trans-A2B2-, A3B-, and trans-AB2C-porphyrins bearing aryl and arylethynyl substituents. The porphyrins were prepared by the acid-catalyzed condensation of dipyrromethanes with aldehydes followed by oxidation with p-chloranil or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Optimal conditions for the condensation were identified after examining various reaction parameters such as solvent composition, acid concentration, and reaction time. The conditions identified (for aromatic aldehydes: EtOH/H2O 4:1, [DPM] = 4 mM, [aldehyde] = 4 mM, [HCl] = 38 mM, 16 h; for arylethynyl aldehydes: THF/H2O 2:1, [DPM] = 13 mM, [aldehyde] = 13 mM, [HCl] = 150 mM, 3 h) resulted in the formation of porphyrins in yields of 9-38% without detectable scrambling. This synthesis is compatible with diverse functionalities such as ester or nitrile. In total, 20 new trans-A2B2-, A3B-, and trans-AB2C-porphyrins were prepared. The scope and limitations of the two sets of reaction conditions have been explored. The methodological advantage of this approach is its straightforward access to building blocks and the formation of the porphyrin core in higher yields than by any other methodology and by using environmentally benign and nonhazardous chemicals.
- Nowak-Krl, Agnieszka,Plamont, Rmi,Canard, Gabriel,Edzang, Judicaelle Andeme,Gryko, Daniel T.,Balaban, Teodorsilviu
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supporting information
p. 1488 - 1498
(2015/01/30)
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- Control of absorption properties of tetraazaporphyrin group 15 complexes by modification of their axial ligands
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Tetraazaporphyrin (TAP) complexes with group 15 elements (phosphorus(v) or arsenic(v)) containing two axial OH ligands showed reversible spectroscopic changes with acid or base doping. Spectroscopic and theoretical analysis revealed that the modification of axial ligands can tune the interaction between peripheral substituents and the TAP macrocycle.
- Furuyama, Taniyuki,Asai, Mitsuo,Kobayashi, Nagao
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supporting information
p. 15101 - 15104
(2015/02/19)
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- Synthesis of trans-A2B2- and trans-A2BC-porphyrins with polar 4′-(dimethylamino)tolan-4-yl substituents, and a screening protocol for vapor-phase deposition on metal surfaces
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The role of polar 4-[p-(dimethylamino)phenylethynyl]phenyl substituents, with a calculated dipole moment of 3.35 Debye, in the self-assembly of trans-A2B2- and A2BC-substituted porphyrins was explored in the solid state by X-ray crystallography, and on an Au(111) surface by scanning tunneling microscopy (STM). Our results demonstrate that the dipolar character of these substituents blocks the 2D self-assembly of porphyrins into larger ordered domains on Au(111) at low coverage, whereas antiparallel dipole - dipole interactions govern the molecular ordering in the crystal. The STM analysis revealed an adaptation of the conformation of the prochiral building blocks and a site-selectivity of the adsorption. We present a general protocol for testing the suitability of higher-molecular-weight compounds, such as porphyrins, to be deposited on surface by sublimation in ultra-high vacuum (UHV). This protocol combines classical methods of chemical analysis with typical surface science techniques.
- Alberti, Mariza N.,Nowakowska, Sylwia,Tzirakis, Manolis D.,Nowakowski, Jan,Fesser, Petra,Schweizer, W. Bernd,Shchyrba, Aneliia,Thilgen, Carlo,Jung, Thomas A.,Diederich, Fran?ois
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supporting information
p. 5705 - 5719
(2014/10/16)
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- Transport of macrocyclic compounds across phospholipid bilayers by umbrella-rotaxanes
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We report the synthesis and assembly of umbrella-rotaxanes with transmembrane transport properties. We describe their amphomorphism and validate their ability to penetrate and cross phospholipid bilayers. Furthermore we present the strategy to release the macrocyclic compound by enzymatic cleavage inside egg yolk phosphatidylcholine (EYPC) liposomes. The Royal Society of Chemistry.
- Chhun, Christine,Richard-Daniel, Josée,Kempf, Julie,Schmitzer, Andreea R.
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supporting information
p. 6023 - 6028
(2013/09/12)
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- Chemical synthesis and evaluation of 17α-alkylated derivatives of estradiol as inhibitors of steroid sulfatase
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Steroid sulfatase (STS) controls the levels of 3-hydroxysteroids available from circulating steroid sulfates in several normal and malignant tissues. This and the known involvement of active estrogens and androgens in diseases such as breast and prostate cancers thus make STS an interesting therapeutic target. Here we describe the chemical synthesis and characterization of an extended series of 17α-derivatives of estradiol (E2) using different strategies. A variant of the samarium-Barbier reaction with stoichiometric samarium metal and catalytic Kagan reagent formation was used for introducing low reactive benzyl substrates in position 17 of estrone (E1) whereas heterocyclic substrates were metalated and reacted with either the carbonyl or the 17-oxirane of E1. In vitro evaluation of the inhibitory potency of the new compounds against STS identified new inhibitors and allowed a more complete structure-activity relationship study of this family of 17α-derivatives of E2.
- Fournier, Diane,Poirier, Donald
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p. 4227 - 4237
(2011/11/12)
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- Synthesis of lipophilic N 9-benzylguanine derivatives
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Lipophilic N9-benzylguanine derivatives were synthesized from the arylalkylation of 2-N-acetylguanine with substituted benzyl bromides. Georg Thieme Verlag Stuttgart - New York.
- McCallum, Jeremy E. B.,Huston, Kenneth G.,McSweeney, Jacqueline M.,Rucker, Brandie G.
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scheme or table
p. 2871 - 2874
(2011/02/23)
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- Solution and thin-film aggregation studies of octasubstituted dendritic phthalocyanines
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The synthesis and solution and thin-film characterization of eight octasubstituted dendritic phthalocyanines (Pcs) and their zinc complexes are reported. The Pc chromophore was substituted in the 2,3,9,10,16,17,23,24- positions with three generations of b
- Kernag, Casey,McGrath, Dominic
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experimental part
p. 9 - 21
(2010/01/16)
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- Synthesis of a soluble ureido-naphthyridine oligomer that self-associates via eight contiguous hydrogen bonds
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(Chemical Equation Presented) An iterative synthetic route to organic-soluble ureido-naphthyridine oligomers has been developed. Use of this protocol allowed synthesis of a short ureido-naphthyridine oligomer, which presents a self-complementary DDAADDAA hydrogen bonding array (D = hydrogen bond donor, A = hydrogen bond acceptor). Strong self-association via eight hydrogen bonds was observed in organic solution.
- Mayer, Michael F.,Nakashima, Shoji,Zimmerman, Steven C.
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p. 3005 - 3008
(2007/10/03)
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- New ruthenium catalysts containing chiral Schiff bases for the asymmetric hydrogenation of acetophenone
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A series of new chiral N4-Schiff bases, containing amine or sulfonamide functionalities has been synthesized. Coupled with ruthenium catalysts, these Schiff bases induce interesting results in the hydrogenation of acetophenone: complete conversion and 76% ee were obtained with the catalytic system Ru(PPh3)3Cl2/(1R,2R)-N,N′-bis-(2- p-tosylaminobenzylidene)-1,2-diphenylethylenediamine. A very important phosphine co-ligand effect was observed on both activity and enantioselectivity of the catalysts. However, without the co-ligand, we obtained an enantioselectivity for the (R)-enantiomer, whereas with nonchiral co-ligand an enantioselectivity for the (S)-enantiomer was observed.
- Karame, Iyad,Jahjah, Mohamed,Messaoudi, Abdelhalim,Tommasino, M. Lorraine,Lemaire, Marc
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p. 1569 - 1581
(2007/10/03)
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- Benzopyran or thiobenzopyran derivatives
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The present invention provides novel benzopyran compounds, pharmaceutically acceptable salts thereof and stereoisomers thereof where the benzopyran compounds of the invention are compounds according to Formula I: The present invention further provides pharmaceutical compositions which possess anti-estrogenic activity and comprise at least one benzopyran compound of the invention and a method of treating breast cancer by administration of an effective amount of a benzopyran compound provided by the present invention.
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Page/Page column 55
(2010/01/31)
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- A new synthetic route to donor-acceptor porphyrins
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Some new donor-acceptor porphyrins have been prepared based on a metallated bis(ethynyl) porphyrin core. 4-(Dimethylamino)phenyl was used as the donor group and 4-nitrophenyl, 4-cyanophenyl and 5-nitrothiazoyl as the acceptor groups. Dipyrrylmethane was used for large scale porphyrin ring synthesis because the absence of methylene substituents reduces the difficulty of substituent scrambling that occurs during porphyrin synthesis.
- Plater, M.John,Aiken, Stuart,Bourhill, Grant
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p. 2405 - 2413
(2007/10/03)
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- Supramolecular polymer chemistry: Design, synthesis, characterization, and kinetics, thermodynamics, and fidelity of formation of self-assembled dendrimers
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Dendrimers 1a-d were synthesized in 10 steps from dendrons 4-7, bromobenzene and succinic anhydride. Tetraacids 1e and 1f were prepared in an analogous fashion. The aggregation of 1a-f was studied in solution by size exclusion chromatography (SEC), vapor pressure osmometry (VPO), low angle laser light scattering (LLS), small angle neutron scattering (SANS), and by 1H NMR. The data are consistent with a stable, discrete hexameric aggregate for 1b-d in methylene chloride, non-discrete polymeric aggregates for 1a, 1e, and 1f, and monomers for all compounds in tetrahydrofuran and dimethyl sulfoxide. Kinetic and thermodynamic studies and mixing experiments confirmed the highly cooperative nature of the self-assembly process.
- Zeng, Fanwen,Zimmerman, Steven C,Kolotuchin, Sergei V,Reichert, David E.C,Ma, Yuguo
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p. 825 - 843
(2007/10/03)
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- Synthesis of (S,S)-1,2-bis(3,5-di-tert-butylphenyl)ethane-1,2-diol
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The synthesis of (S,S)-1,2-bis(3,5-di-tert-butylphenyl)ethane-1,2-diol (98.6% ee), which should be useful as a chiral ligand of catalysts in asymmetric inductions, is described.
- Ishimaru, Kaori,Monda, Keiji,Yamamoto, Yohsuke,Akiba, Kin-Ya
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p. 575 - 580
(2007/10/03)
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- Anxiolytic activity of analogues of 4-benzylamino-2-methyl-7H- pyrrolo[2,3-d]pyrimidines
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An extensive series of analogues of the lead anxiolytic 4-benzylamino- 2-methylpyrrolo[2,3-d]pyrimidine 1 was synthesized and evaluated in the Geller-Seifter conflict test for anxiolytic activity to discover a less toxic derivative. Analysis of the SAR revealed that the most potent compounds were those with meta substituents on the benzylamino ring. In this group the most promising derivatives were 4-[bis(3,5-dimethylamino)]benzylamino-2-methyl- 7H-pyrrolo[2,3-d]pyrimidine 12 and 4-(3,5-dimethylbenzylamino)-2-methyl-7H- pyrrolo[2,3-d]pyrimidine 24. Potential metabolites of 12 were synthesized and checked for their anxiolytic activity. Less toxic analogues of the second lead 24 were prepared by extending the alkyl groups attached to the benzene ring moiety. The addition of a fluoro substituent to the benzene moiety in the extended alkyl chain analogue 4-(3,5-diethyl-2-fluorobenzylamino)2- methyl-7H-pyrrolo[2,3-d]pyrimidine 34 resulted in a compound with a longer duration of activity relative to its analogue 4-(3,5-diethylbenzylamino)-2- methyl-7H-pyrrolo[2,3-d]pyrimidine 26.
- Meade, Eric A.,Sznaidman, Marcos,Pollard, Gerald T.,Beauchamp, Lilia M.,Howard, James L.
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p. 363 - 374
(2007/10/03)
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- Photolysis of (2,4,6-Tri-t-butylphenyl)bis(trimethylsilyl)phosphine
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The photolysis of (2,4,6-tri-t-butylphenyl)bis(trimethylsilyl)phosphine in benzene gave products suggesting homolytic P-C bond cleavage followed by rearrangement and coupling.
- Yoshifuji, Masaaki,Shimura, Kazuho,Toyota, Kozo
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p. 1980 - 1983
(2007/10/02)
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- 3,5-Di-tert-butylstyrenes: Synthesis of Bulky Polymer Building Blocks
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We report the synthesis of 3,5-di-tert-butylstyrene (5).The alkylation of toluene with tert-butylchloride establishes the 1,3,5-substitution pattern.A Wittig reaction introduces the C1 unit.This and similar bulky styrene derivatives will be used as special building blocks for polymer design. - Keywords: 3,5-Di-tert-butylstyrenes, Bulky Polystyrene Monomers, 1H NMR Spectra
- Risch, Nikolaus,Meyer-Roscher, Bernd,Langhals, Maria
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p. 141 - 144
(2007/10/02)
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- Remote steric effects on the disproportionation / recombination ratio of cumyl radicals
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The disproportionation / combination ratio in the reaction between two 3,5-di-tert-butylcumyl radicals, generated by thermolysis of the corresponding diazene, is 0.21 +/- 0.03 at 60 deg C in benzene.This is much larger than the value of 0.06 found for the unsubstituted cumyl radicals.It is suggested that the tert-butyl groups hinder the formation of a parallel association complex, which has been proposed to account for the much smaller amount of disproportionation in the reaction between benzylic radicals as compared with alkyl radicals.
- Kopecky, Karl R.,Yeung, Mei-Yuk
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p. 374 - 376
(2007/10/02)
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- Preparation of Diaryl and Aryl tert-Butyl α-Thioxoketones
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The preparation of the α-haloketones 6, 13-16, 19, and 20 is reported. 13 or its precursor, the acyloin 9, respectively, is conveniently obtained by a Seebach synthesis. - Reaction of the haloketones with tetraethylammonium thiosulfate (21) yields the Bunte salts 22-27 wich form the thioketones 28-33 on cleavage with aqueous alkali. 29 is stable as a crystalline, blue monomer in contrast with other aromatic α-thioxoketones.This ist also true for the aromatic-aliphatic derivatives 30 and 31 as well as their isomers 32 and 33 wich do not dimerize.
- Hahn, Bernd,Koepke, Brigitte,Voss, Juergen
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