Study of acidity and coordination properties of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin in the system of 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile

Spectrophotometric titration method was used to study the acidic properties of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin in the presence of a deprotonated agent, 1,8-diazabicyclo[5.4.0] undec-7-ene, in acetonitrile. The spectral characteristics of the ionized forms and combined ionization constant for the first and second stages were revealed. The reaction of complex formation between the dianionic forms of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin and zinc acetate was studied.     

Influence of substituents structure and their electronic effects on acid-base and complexing properties of 5,10,15,20-tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin

5,10,15,20-Tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin has been prepared, and its acid-basic properties have been studied in acetonitrile by titration with 1,8-diazabicyclo [5.4.0]undec-7-ene and perchloric acid. The substituted porphyrin ability towards complex formation with zinc acetate has been studied in acetonitrile and acetonitrile, 1,8-diazabicyclo [5.4.0]undec-7-ene media. Spectral properties of neutral and ionic forms of 5,10,15,20-tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin and its zinc complex have been determined; constants of acid and basic ionization of the ligand have been estimated. Kinetic parameters of the porphyrin complex formation with zinc via molecular and ionic mechanism have been analyzed. The substituents effect on the studied properties is discussed.     

Synthesis and spectrophotometric study of the acid-base and complexing properties of 2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin in acetonitrile

2,3,7,8,12,13,17,18-Octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin has been synthesized, and its acid-base and complexing properties in the systems 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile, acetonitrile-Zn(OAc)₂, and 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile-Zn(OAc)₂ have been studied by spectrophotometry. Titration of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin with 1,8-diazabicyclo[5.4.0]undec-7-ene is accompanied by successive deprotonation of the pyrrole nitrogen atoms with formation of the corresponding mono- and dianion. The overall acid dissociation constant of the title compound has been determined. The complexation of neutral and doubly deprotonated 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin with Zn(OAc)₂ has been studied, and kinetic parameters for the formation of the zinc complex according to the molecular and ionic mechanisms have been determined. Extra coordination of 1,8-diazabicyclo[5.4.0]undec-7-ene by the zinc complex of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin.     

Spectrophotometric study of equilibrium association of cationic acids of tetraphenylporphyrin β-bromo-derivatives in acetonitrile-perchloric acid system at 298 K

The basic properties of 2-bromo-5,10,15,20-tetraphenylporphyrin (I), 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin (II) and 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin (III) in the system of acetonitrile-perchloric acid at 298 K were studied using a method of spectrophotometric titration. The protonation of endocyclic nitrogen atoms of tetrapyrrole macrocycles was found to occur in two stages, therewith the increase in the number of bromine atoms in the structure of the macrocycle made easier the addition of the first proton compared with the second one. The ionization constant and the concentration ranges of existence of mono- and dication forms of the compounds were determined.     

Coordination properties of molecular and anionic forms of 5,10,15,20,21-pentaphenyl-2,3,7,8,12,13,17,18-octaethylporphyrin in acetonitrile

Acid and coordination properties of 5,10,15,20,21-pentaphenyl-2,3,7,8,12,13,17,18-octaethylporphine in 1,8-diazabicyclo[5.4.0]undec-7-ene–acetonitrile system at 298 K have been studied by spectrophotometric titration. It has been found that titration causes deprotonation of nitrogen atom of the pyrrole ring to produce monodeprotonated form. Acid dissociation constant of the compound in 1,8-diazabicyclo[5.4.0]undec-7-ene–acetonitrile system at 298 K has been determined. Complexation of molecular and deprotonated forms of the ligand with silver nitrate has been studied, kinetic parameters of the corresponding reactions have been obtained. Kinetics of silver complexation with the studied ligand by ionic and molecular mechanism has been analyzed.     

Complex formation of β-brominated tetraphenylporphyrins and metal exchange of their cadmium complexes with <Emphasis Type="Italic">d</Emphasis>-metal salts in dimethylformamide

Complex formation of zinc and copper(II) acetates with tetraphenylporphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin, 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin, and 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin in N,N-dimethylformamide has been studied. The rate constants determined in the study of the complex formation and the metal exchange reactions have been compared.     

Synthesis of β-Bromo-Substituted Cu(II) Tetraphenylporphyrinates

Bromination reactions of Cu(II) 5,10,15,20-tetraphenylporphyrinate with N-bromosuccinimide in chloroform and chloroform–dimethylformamide mixture and complexation of 2-bromo-5,10,15,20-tetraphenylporphyrin and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with copper(II) acetate in dimethylformamide have been studied. Mono-, tetra-, and octabromo-substituted Cu(II) porphyrinates have been synthesized. Obtained compounds have been identified by electronic absorption spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis.     

Synthesis and properties of ms- and β-substituted Pt(II) and Pt(IV) tetraphenylporphyrinates

The interaction of 5,10,15,20-tetraphenylporphyrin, 5,10,15,20-tetra-(4-chlorophenyl)porphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin, and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with platinum(II) chloride in boiling phenol has been studied. The corresponding platinum(II) porphyrinates have been synthesized; their subsequent treatment with bromine in chloroform resulted in platinum(IV) porphyrinates. The Pt(II) and Pt(IV)(Br)₂ porphyrinates have been identified by elemental analysis, electron absorption, IR, and ¹H NMR spectroscopy.     

Spectral and complex-forming properties of β-bromo-substituted porphyrins in N,N-dimethylformamide

Contributions of structural and electronic effects to the reactivity and chromophore properties of tetrapyrrole macrocycles modified by bromine atoms were revealed on the basis of the kinetic data on the complex formation of 2-bromo-5,10,15,20-tetraphenylporphyrin, 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin, and 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin with zinc(II) and copper(II) acetates in N,N-dimethylformamide, and also by measuring spectral characteristics of porphyrin ligands and zinc and copper porphyrinates.     

An improved protocol for the synthesis of antipodal β-tetrabromo-tetraphenylporphyrin and the crystal structure of its Zn(II) complex

This work reports an improved protocol for the regioselective synthesis of 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin (H₂TPPBr₄) and the crystal structure of its Zn(II) complex which shows saddle shaped geometry.     

Preparation and characterization of 6-substituted 1,8-diazabicyclo[5.4.0]undec-7-ene

The lithium 1,8-diazabicyclo[5.4.0]undec-6-ide ( 1 ) prepared from 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and n-butyllithium reacts with alkyl halides and carbonyl compounds such as benzophenone, acetophenone, and benzaldehyde to give 6-substituted DBU derivatives in good yields. The reaction behavior of 6-substi-tuted DBU was also investigated.     

Spectrophotometric study of the complexing properties of 2,3,7,8,12,13,17,18-Octaethyl-5,10,15-trinitroporphyrin and its dianion toward Zn(OAc)2 in acetonitrile

Complexing properties of 2,3,7,8,12,13,17,18-octaethyl-5,10,15-trinitroporphyrin and its dianionic form in the systems acetonitrile-Zn(OAc)₂ and 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile-Zn(OAc)₂ have been studied by spectrophotometric titration. Zinc complexes of 2,3,7,8,12,13,17,18-octaethyl-5,10,15-trinitroporphyrin have been characterized by spectral data, and kinetic parameters of the complex formation according to the molecular and ionic mechanisms have been analyzed.     

Ionic liquids on the basis of 2,3,4,6,7,8,9,10-octahydropyrimido-[1,2-a]azepine (1,8-diazabicyclo[5.4.0]undec-7-ene)

New ionic liquids containing alkyl and polyfluoroalkyl substituents and various anions were synthesized from 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepinium ion (1,8-diazabicyclo[5.4.0]undec-7-en-8-ium). Their NMR spectra and miscibility with water and organic solvents were studied.     

Palladium-catalysed dimerization of isoprene with carbon dioxide in the presence of organotin ethoxide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)

The palladium-catalysed dimerization of isoprene with carbon dioxide is promoted by treatment wiht tributyltin ethoxide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).     

Trifluoromethanesulfonate,trifluromethylsulfonylimide, and bis(trifluoromethylsulfonyl)imide salts and ionic liquids based on 1,8-diazabicyclo[5.4.0]undec-7-ene and 1,5-diazabicyclo[ 4.3.0]non-5-ene

Trifluoromethanesulfonate, trifluoromethylsulfonylimide, and bis(trifluoromethylsulfonyl)imide salts and ionic liquids were synthesized from 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine (1,8-diazabicyclo[5.4.0]undec-7-ene) and 2,3,4,6,7,8-hexahydropyrrolo[1,2-a]pyrimidine (1,5-diazabicyclo[4.3.0]non-5-ene). Their physicochemical properties, spectral parameters, and some chemical transformations were studied.     

Unique cascade ring-opening/cyclization reaction of azlactones and DBU or DBN: Synthesis of new pyrrolam A analogues

1-Azabicyclo[3.3.0]oct-3-en-2-one derivatives were synthesized efficiently through the facile cascade reaction of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) with arylidene azlactones. This research provides a straightforward procedure for the synthesis of a novel class of multicyclic semi-alkaloids which shows good antimicrobial activity. Under catalyst-free, mild, and solventless condition, a wide range of fused tricyclic derivatives was obtained in high yields.     

Sonochemical fluorination of heterocyclic nitro compounds with Selectfluor

Methine and methylene groups attached to a nitro function and heterocycle (and Ph for CH) were rapidly mono- or di-fluorinated by reaction with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis-tetrafluoroborate (Selectfluor) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), preferably with ultrasonic irradiation.     

Sonochemical fluorination of heterocyclic nitro compounds with Selectfluor™ (F-TEDA-BF4)

CH and CH₂ groups attached to a heterocycle and a nitro function were rapidly mono- or difluorinated by reaction with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis-tetrafluoroborate (Selectfluor) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), preferably with ultrasonic irradiation.     

Cycloadducts of methyl hydroxyalkynoates and DBU: Transformation into tethered furan-2(5H)-one and caprolactam structures

Russian Journal of Organic Chemistry - Cycloadducts of 1,8-diazabicyclo[5.4.0]undec-7-ene and methyl 4-hydroxyalk-2-ynoates, octahydro-5H,9H-[1,3]oxazolo[2′,3′:...     

Synthesis and spectrophotometric study of deprotonation of octamethylporphyrin derivatives with 1,8-diazabicyclo[5.4.0]undec-7-ene in acetonitrile

Acidic properties of synthesized 5,10,15,20-tetrakis(4′-tert-butylphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin and 5,10,15,20-tetrakis(3′,5′-di-tert-butylphenyl)-2,3,7,8,12,13,17,18-octamethylporphyrin have been studied by spectrophotometry. Deprotonation of the intracyclic nitrogen atoms with 1.8-diazabicyclo [5.4.0]undec-7-ene in acetonitrile occurs in two steps. Deprotonation constants and ranges of the porphyrinsanionic forms existence have been determined, and influence of the peripheral substituents on acidic properties of the macrocyclic ligand has been elucidated.