Search results for "Free base"
showing 10 items of 27 documents
Triplet-triplet energy transfer controlled by the donor-acceptor distance in rigidly held palladium-containing cofacial bisporphyrins.
2005
Eleven new complexes, including mono-, heterobi-, and homobimetallic cofacial bisporphyrins, (Pd)H 2 DPS, (M)H 2 DPX, (M)H 2 DPB, (PdZn)DPS, (PdZn)DPX, (Pt) 2 DPX, (M) 2 DPB (M=Pd, Pt), and (Pt)P (DPS 4 - = 4,6-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]dibenzothiophene tetraanion, DPX 4 - = 4,5-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]-9,9-dimethylxanthene tetraanion, DPB 4 - =1,8-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]biphenylene tetraanion, P 2 - = 5-phenyl-2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrin dianion) have been synthesized and characterized. The photophysical properties of the donor (M)P (M=Pd or Pt, P= porphy…
Adducts of free-base meso-tetraarylporphyrins with trihaloacetic acids: Structure and photostability
2020
Abstract Four diverse meso-tetraarylporphyrins in the form of diprotonated adducts with trifluoro-, trichloro-, tribromoacetic acids and acetic acid were investigated in benzene solution. Despite similar structural distortion of the chromophore system due to protonation, the respective adducts demonstrated different photostability when exposed to UV irradiation. The trifluoro- and trichloroacetic adducts, and the acetic acid one, showed some common features both molecular and in the mechanism of photodegradation. However, the tribromo-derivative decayed according to a different kinetic scheme, revealing a considerable impact of the bromine atoms upon the pyrrole units of the porphyrin macro…
Synthesis, characterization and electrochemistry of bismuth porphyrins: X-ray crystal structure of (OEP)Bi(SO3CF3)
2000
The metalation of several free base porphyrins by the bismuth salts Bi(NO3)3 and Bi(SO3CF3)3 in DMF or pyridine is described. The resulting stable Bi(III) porphyrin complexes are characterized by electrochemistry, 1H NMR and UV-vis spectroscopy. The structure of ( OEP ) Bi ( SO 3 CF 3) was also determined by single-crystal X-ray diffraction and shows that ( OEP ) Bi ( SO 3 CF 3) exists as a dimer which is stabilized by electrostatic interactions in which the two [(OEP)Bi]+ cations are linked via oxygen atoms of two symmetrically related [Formula: see text] anions, leading to a heptacoordinated bismuth center. Electrochemical oxidation of ( OEP ) Bi ( SO 3 CF 3) and ( T p TP ) Bi ( SO3CF3 )…
Design of Triads for Probing the Direct Through Space Energy Transfers in Closely Spaced Assemblies
2013
Using a selective stepwise Suzuki cross-coupling reaction, two trimers built on three different chromophores were prepared. These trimers exhibit a D(^)A1-A2 structure where the donor D (octa-β-alkyl zinc(II)porphyrin either as diethylhexamethyl, 10a, or tetraethyltetramethyl, 10b, derivatives) through space transfers the S1 energy to two different acceptors, di(4-ethylbenzene) zinc(II)porphyrin (A1; acceptor 1) placed cofacial with D, and the corresponding free base (A2; acceptor 2), which is meso-meso-linked with A1. This structure design allows for the possibility of comparing two series of assemblies, 9a,b (D(^)A1) with 10a,b (D(^)Â1-A2), for the evaluation of the S1 energy transfer for…
Synthesis, characterization and X-ray crystal structures of cyclam derivatives. Part VI. Proton binding studies of a pyridine-strapped 5,12-dioxocycl…
2005
The 14-membered cyclic diamide 1,4,8,11-tetraazacyclotetradecane-5,12-dione (5,12-dioxocyclam) can be considered as a trans-autodiprotected tetraazamacrocycle and provides a convenient starting material for the preparation of macrobicyclic receptors. As an example, the secondary amine nitrogen atoms located at the 1 and 8 positions were cross-bridged with a 1,3-pyridyl strap, affording the constrained ansa-dioxocyclam ligand 1,9,12,18,22-pentaazatricyclo[7.6.6.13,7]docosa-3,5,7(22)-triene-13,19-dione (L1). The proton binding properties of this cage-type compound, which possesses a hemispherical cavity, were fully investigated by spectroscopic (IR, NMR, UV, MALDI-TOF MS), quantum chemical, a…
Regioselective C–H amination of free base porphyrins via electrogenerated pyridinium-porphyrins and stabilization of easily oxidized amino-porphyrins…
2020
Four free base aminoporphyrins were synthesized in two steps via regioselective anodic nucleophilic substitution with pyridine followed by ring opening of the electrogenerated pyridinium with piperidine. The X-ray crystallographic structure of the unstable 2-aminotetraphenylporphyrin was solved. Protonation of this latter compound leads to the stable diiminium porphyrin salt.
Synthesis and Physicochemical Characterization of Bis(macrocycles) Involving a Porphyrin and a meso ‐Substituted Corrole – X‐ray Crystal Structure of…
2005
A very efficient, simple synthesis of face-to-face porphyrin–corrole free-bases bearing substituents at the meso positions of the corrole ring is reported. Starting from the (porphyrin–aldehyde)zinc species 1Zn, porphyrin–corrole free-bases (3M, 3C) are obtained in two steps, in fairly good yields (40–43 %), compared to 11 steps for their corrole β-pyrrole-substituted counterparts. Moreover, the possibility to directly synthesize the free-base (porphyrin–corrole)cobalt complex (5M or 5C) allows for the further preparation of heterodimetallic derivatives. Crystals of the bis(pyridine) adduct of 5M have been grown; the molecular structure clearly shows that the two pyridine molecules are coor…
Electrochemical and Spectroelectrochemical Properties of Free-Base Pyridyl- and N -Alkyl-4-Pyridylporphyrins in Nonaqueous Media
2015
International audience; Twelve structurally related pyridyl and meso-N-methylpyridylporphyrin derivatives are investigated electrochemically in different nonaqueous media. The UV/Vis spectrum of each newly investigated porphyrin was measured before and after electro-reduction and, based on this data, the site of electron transfer is proposed. An interaction occurs between the meso-pyridyl or meso-N-alkyl-4-pyridyl substituents and the porphyrin p-ring system, the magnitude of which depends upon the number of linked pyridyl or N-alkyl-4-pyridyl groups in the compound, the solvent, the supporting electrolyte, and/or other anions added to the solution.
Singlet and triplet energy transfers in tetra-(meso-truxene)zinc(II)- and tetra-(meso-tritruxene)zinc(II) porphyrin and porphyrin-free base dendrimer…
2011
The synthesis, optical properties, and energy transfer features of four dendrimers composed of meso-tetrasubstituted zinc(II) porphyrin (ZnP) or a free base (P) central core, where the substituents are four truxene (Tru) or four tritruxene dendrons (TriTru), TruP, TriTruP, TruZnP, and TriTruZnP, are reported. Selective excitation of the truxene donors results in a photoinduced singlet energy transfer from the truxenes to the porphyrin acceptor. The rates for singlet energy transfer (k(ET)), evaluated from the change in the fluorescence lifetime of the donors (Tru and TriTru) in the presence and absence of the acceptor (P or ZnP) for TruP, TruZnP, TriTruP, and TriTruZnP, are 5.9, 1.2, 0.87, …
Application of molecularly imprinted polymers in supercritical fluid chromatography
2000
Molecularly imprinted polymers (MIPs), for the templates free base racemic propranolol and the L-enantiomer of phenylalanine anilide (L-PA), were investigated as stationary phases in supercritical fluid chromatography (SFC). Large retention differences were observed on the propranolol MIP for both the template molecule and the structural analogue metoprolol compared to that observed on the corresponding blank polymer. Mobile phase composition and solute concentration were found to affect this retention behaviour. The phenylalanine anilide MIP (L-PA MIP) was found to be enantioselective in SFC with stronger retention observed for the template enantiomer. Throughout the study, characteristic …