62938-08-3Relevant academic research and scientific papers
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
Krause, Maren,von der Stück, René,Brünink, Dana,Buss, Stefan,Doltsinis, Nikos L.,Strassert, Cristian A.,Klein, Axel
supporting information, (2021/01/25)
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.
Aerobic C(sp2)-H Hydroxylations of 2-Aryloxazolines: Fast Access to Excited-State Intramolecular Proton Transfer (ESIPT)-Based Luminophores
G?bel, Dominik,Clamor, Nils,Lork, Enno,Nachtsheim, Boris J.
supporting information, p. 5373 - 5377 (2019/06/07)
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.
An efficient synthesis of porphyrins with different meso substituents that avoids scrambling in aqueous media
Nowak-Krl, Agnieszka,Plamont, Rmi,Canard, Gabriel,Edzang, Judicaelle Andeme,Gryko, Daniel T.,Balaban, Teodorsilviu
supporting information, p. 1488 - 1498 (2015/01/30)
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.
Control of absorption properties of tetraazaporphyrin group 15 complexes by modification of their axial ligands
Furuyama, Taniyuki,Asai, Mitsuo,Kobayashi, Nagao
supporting information, p. 15101 - 15104 (2015/02/19)
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.
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
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
supporting information, p. 5705 - 5719 (2014/10/16)
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.
Transport of macrocyclic compounds across phospholipid bilayers by umbrella-rotaxanes
Chhun, Christine,Richard-Daniel, Josée,Kempf, Julie,Schmitzer, Andreea R.
supporting information, p. 6023 - 6028 (2013/09/12)
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.
Chemical synthesis and evaluation of 17α-alkylated derivatives of estradiol as inhibitors of steroid sulfatase
Fournier, Diane,Poirier, Donald
experimental part, p. 4227 - 4237 (2011/11/12)
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.
Synthesis of lipophilic N 9-benzylguanine derivatives
McCallum, Jeremy E. B.,Huston, Kenneth G.,McSweeney, Jacqueline M.,Rucker, Brandie G.
scheme or table, p. 2871 - 2874 (2011/02/23)
Lipophilic N9-benzylguanine derivatives were synthesized from the arylalkylation of 2-N-acetylguanine with substituted benzyl bromides. Georg Thieme Verlag Stuttgart - New York.
Solution and thin-film aggregation studies of octasubstituted dendritic phthalocyanines
Kernag, Casey,McGrath, Dominic
experimental part, p. 9 - 21 (2010/01/16)
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
Synthesis of a soluble ureido-naphthyridine oligomer that self-associates via eight contiguous hydrogen bonds
Mayer, Michael F.,Nakashima, Shoji,Zimmerman, Steven C.
, p. 3005 - 3008 (2007/10/03)
(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.
