scholarly journals Synthesis and Spectroscopic Properties of Low-Symmetry Tribenzoporphyrazines with Annulated 6H-1,4-Diazepine Ring

2008 ◽  
Vol 61 (4) ◽  
pp. 262 ◽  
Author(s):  
Maria Pia Donzello ◽  
Claudio Ercolani ◽  
Luisa Mannina ◽  
Elisa Viola ◽  
Alëna Bubnova ◽  
...  
Keyword(s):  
1H Nmr ◽  
Variable Temperature ◽  
Sodium Ethoxide ◽  
Spectroscopic Properties ◽  
Free Base ◽  
Free Energy Of Activation ◽  
Aquo Complex ◽  
Visible Spectra ◽  
Uv Visible ◽  
Low Symmetry

Template co-condensation of 2,3-dicyano-5,7-diphenyl-6H-1,4-diazepine 1 with 10-fold molar excess of phthalodinitrile 2 in the presence of MgII propoxide or butoxide in the corresponding alcohol leads to a mixture of MgII-diazepinoporphyrazines 3–6 from which the low symmetry 3:1 species 3, which contains three annulated benzene and one 1,4-diazepine rings, is separated by column chromatography as the aquo complex, [2,4-diphenyltribenzo[b,g,l][1,4]diazepino[2,3-q]porphyrazinato(aquo)magnesium(ii)], [Bz3DzPzMg(H2O)]. The complex 3 can be demetalated in acetic or trifluoroacetic acids under mild conditions with formation of the corresponding free-base [Bz3DzPzH2] 3a. This latter is also formed by co-cyclotetramerization of the same precursors 1 and 2 in the presence of sodium ethoxide in ethanol or lithium butoxide in butanol followed by demetalation of the intermediate disodium or dilithium salts in acid medium. The constitution and structure of the obtained compounds were established on the basis of elemental analysis, mass spectrometry, and 1H NMR spectra. The variable temperature 1H NMR measurements provide evidence that in porphyrazines 3 and 3a the 1,4-diazepine ring exists predominantly in the 6H-form over a wide temperature range. The free energy of activation for the inversion of the 1,4-diazepine ring determined for 3 is 45.6 ± 1.7 kJ mol–1. Solution UV-visible spectra measurements in acidic media (CH2Cl2/CF3COOH) provide evidence that the MgII complex 3 is easily protonated on the meso-N atom of the porphyrazine macrocycle followed by slow demetallation with formation of the free base 3a in its neutral form or as a species protonated on the diazepine ring.

Solvent and acidity effects on the UV-visible spectra and protonation-deprotonation of free-base octaethylcorrole

2008 ◽  
Vol 12 (01) ◽  
pp. 1-10 ◽  
Author(s):  
Zhongping Ou ◽  
Hongxia Sun ◽  
Weihua Zhu ◽  
Zulin Da ◽  
Karl M. Kadish
Keyword(s):  
Equilibrium Constants ◽  
Visible Spectrum ◽  
Soret Band ◽  
Free Base ◽  
Tetrabutylammonium Hydroxide ◽  
Experimental Conditions ◽  
Visible Spectra ◽  
Meso Position ◽  
Uv Visible ◽  
Strong Acids

The UV-visible spectrum of free-base octaethylcorrole, (OECor) H 3, was recorded in thirteen different nonaqueous solvents as well as in a mixed acetonitrile/acid solvent containing one of seven different acids. Spectra were also measured in seven different solutions of neat concentrated acid and in CH 3 CN containing piperidine or tetrabutylammonium hydroxide as an added base. The overall data was analyzed as a function of solvent acidity or basicity parameters and the number of protons on the central nitrogens of the macrocycle, the predominant form of the corrole in these solutions being respresented as (OECor)H 3, [ (OECor)H 4]+, [ (OECor)H 2]− or [ (OECor)H ]2− where OECor = trianion of octaethylcorrole. The mono-protonated corrole, [ (OECor)H 4]+, is formed in concentrated acetic acid or in CH 3 CN containing 0.10 M trifluoroacetic acid, H 2 SO 4, HCl , H 3 PO 4 or HClO 4. The mono-deprotonated corrole, [ (OECor)H 2]−, is generated in piperidine while doubly deprotonated [ (OECor)H ]2− exists in solutions of tetrabutylammonium hydroxide. An addition of protons to the macrocycle of [ (OECor)H 4]+ also occurs in the presence of concentrated strong acids and this results in a loss of the characteristic Soret band of the corrole leading presumably to [ (OECor)H 5]2+ where the second proton has been added to a meso-position of the macrocycle. The UV-visible spectral changes upon formation of [ (OECor)H 4]+, [ (OECor)H 2]− or [ (OECor)H ]2− in CH 3 CN were monitored during a titration with the relevent acid or base and equilibrium constants for protonation or deprotonation of (OECor)H 3 were determined using standard equations. The measured logK values are compared to protonation and deprotonation constants obtained for two related corroles and two related porphyrins under the same experimental conditions.

Preparation and UCST-Type Phase Behaviours of Poly(γ-4-methylbenzyl-L-glutamate) Pyridinium Tetrafluoroborate Conjugates in Methanol or Water

2017 ◽  
Vol 70 (3) ◽  
pp. 245 ◽  
Author(s):  
Sheng Liu ◽  
Chenglong Ge ◽  
Ying Ling ◽  
Haoyu Tang
Keyword(s):  
1H Nmr ◽  
Variable Temperature ◽  
Molecular Structures ◽  
Phase Behaviour ◽  
Solution Phase ◽  
Thermally Induced ◽  
Ion Exchange Reaction ◽  
Type Phase ◽  
Uv Visible ◽  
Hydrophilicity And Hydrophobicity

Polymers with ionic liquid (IL) moieties can undergo thermally induced solution phase transitions by adjusting the balance of hydrophilicity and hydrophobicity between the cations and anions of the IL moieties, thus making them attractive candidates towards various applications such as separation, sensing, and biomedicine. In the present study, a series of poly(γ-4-methylbenzyl-l-glutamate) pyridinium tetrafluoroborate conjugates (P1–P4) containing various pyridinium moieties (i.e. pyridinium, 2-methylpyridinium, 3-methylpyridinium, and 4-methylpyridinium) were prepared by nucleophilic substitution between poly(γ-4-chloromethylbenzyl-l-glutamate) and pyridine or methylpyridines with different substituent positions, followed by ion-exchange reaction in the presence of NaBF4. 1H NMR spectroscopy and Fourier transform infrared spectroscopy analyses confirmed the molecular structures of P1–P4. 1H NMR analysis additionally revealed that P1–P4 showed high grafting efficiency in the range of 93–97 %. P1, P3, and P4 exhibited reversible UCST-type phase behaviours in both methanol and water, whereas P2 showed a reversible UCST-type phase behaviour in water only. Variable-temperature UV-visible spectroscopy was used to characterize the solution phase behaviours and UCST-type phase transition temperature (Tpt) values of P1–P4, which were in the range of 24.9–37.2°C in methanol (3 mg mL–1) and 40.9–55.7°C in water (10 mg mL–1). Tpt decreased significantly with decreasing polymer concentrations.

scholarly journals SINTESIS NATRIUM PENTAGAMAVUNONAT DAN UJI STABILITASNYA MENGGUNAKAN SPEKTROFOTOMETER UV-Visible

Molekul ◽  
2006 ◽  
Vol 1 (1) ◽  
pp. 24
Author(s):  
Ely Setiawan ◽  
Trisnowati Trisnowati ◽  
Dadan Hermawan
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Structure Elucidation ◽  
Sodium Ethoxide ◽  
Stability Test ◽  
Spectroscopic Methods ◽  
Sodium Ions ◽  
Uv Visible

A research on the synthesis of sodium pentagamavunonat (Na-PGV-0) and its stability test using UV-Visible spectrophotometer were carried out. The synthesis of Na-PGV-0 carried out by reacting PGV-0 in tetrahydrofuran solvent refluxed with sodium ethoxide in mol comparison (1:2) for two hours. Structure elucidation by spectroscopic methods using UV-Visible, IR, 1H-NMR, 13C-NMR and stability test in water using UV-Visible spectrophotometer. The reaction yields 107,21 % (% w/w) products. A products was soluble in water and methanol. Structure elucidation results indicated that the formed compound where the OH phenolic of pentagamavunon-0 was replaced by sodium ions. Stability test shows that decreasing of sodium 

N-confusedmeso-tetraaryl-substituted free-base porphyrins: determination of protonation and deprotonation constants in nonaqueous media

2015 ◽  
Vol 19 (01-03) ◽  
pp. 251-260 ◽  
Author(s):  
Zhongping Ou ◽  
Xueyan Chen ◽  
Lina Ye ◽  
Songlin Xue ◽  
Yuanyuan Fang ◽  
...  
Keyword(s):  
Tautomeric Form ◽  
Equilibrium Constants ◽  
Single Step ◽  
Free Base ◽  
Nonaqueous Media ◽  
Tautomeric Forms ◽  
Visible Spectra ◽  
Phenyl Rings ◽  
Uv Visible

The protonation and deprotonation reactions for a series N-confused meso-tetraaryl-substituted free-base porphyrins containing electron-donating or electron-withdrawing substituents was monitored in CHCl3and DMF by UV-visible spectroscopy during titrations with trifluoroacetic acid or tetra-n-butylammonium hydroxide. The spectroscopic data was also used to calculate equilibrium constants for these reactions. The examined compounds are represented as (XPh)4NCPH2, where "NCP" represents the N-confused porphyrin π-conjugated macrocycle and X is a CH3O , CH3, H or Cl para-substituent on the four meso-phenyl rings (Ph) of the compound. The porphyrins can exist in two tautomeric forms depending upon the solvent and each tautomer undergoes two stepwise protonation reactions leading to formation of the mono- and bis-protonated porphyrins, [(XPh)4NCPH3]+and [(XPh)4NCPH4]2+. A single step deprotonation is observed for the same compounds in DMF and the product is assigned as [(XPh)4NCPH]-. Comparisons are made between UV-visible spectra of the protonated, neutral and deprotonated forms of the porphyrin and the effect of the porphyrin ring substituents and tautomeric form of the neutral porphyrin on the UV-visible spectra and protonation constants is discussed along with data from DFT calculations.

scholarly journals Synthesis, Spectroscopic Studies and Keto-Enol Tautomerism of Novel 1,3,4-Thiadiazole Derivative Containing 3-Mercaptobutan-2-one and Quinazolin-4-one Moieties

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5441
Author(s):  
Sewara J. Mohammed ◽  
Akam K. Salih ◽  
Mohammad Amin M. Rashid ◽  
Khalid M. Omer ◽  
Karzan A. Abdalkarim
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Solvent Polarity ◽  
Spectroscopic Studies ◽  
Keto Form ◽  
Tautomeric Forms ◽  
Fragmentation Mechanisms ◽  
Visible Spectra ◽  
Thiadiazole Derivative ◽  
Uv Visible

In this study, a novel 1,3,4-thiadiazole derivative containing 3-mercaptobutan-2-one and quinazolin-4-one moieties (Compound 3) is synthesized by the coupling of 2-amino-1,3,4-thiadiazole-5-(3-mercaptobutan-2-one) (Compound 1) with 2-Phenyl-4H-3,1-benzoxazin-4-one (Compound 2) in one molecule moiety. Compound 3 is found to exist as two types of intra-molecular hydrogen bonding with keto-enol tautomerism characters, which is further confirmed using FTIR, 1H-NMR, 13C-NMR, mass spectrometer, and UV-Visible spectra. The 1H-NMR and UV-Visible spectra of Compound 3 are investigated in different solvents such as methanol, chloroform, and DMSO. Compound 3 exhibits keto-enol tautomeric forms in solvents with different percentage ratios depending on the solvent polarity. The 1H-NMR and UV-Visible spectral results show that Compound 3 favors the keto over the enol form in polar aprotic solvents such as DMSO and the enol over the keto form in non-polar solvents such as chloroform. The 13C-NMR spectrum gives two singles at δ 204.5 ppm, due to ketonic carbon, and δ 155.5 ppm, due to enolic carbon, confirming the keto-enol tautomerism of Compound 3. Furthermore, the molecular ion at m/z 43 and m/z 407 in the mass spectrum of Compound 3 and fragmentation mechanisms proposed reveal the existence of the keto and enol forms, respectively.

Synthesis, structure and spectroscopic properties of a porphycene-ReI complex

2011 ◽  
Vol 15 (07n08) ◽  
pp. 622-631 ◽  
Author(s):  
Weina Zhang ◽  
Yi Chang ◽  
Fan Wu ◽  
John Mack ◽  
Nagao Kobayashi ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Single Crystal ◽  
Spectroscopic Properties ◽  
Free Base ◽  
X Ray ◽  
H Nmr ◽  
New Type ◽  
Uv Visible ◽  
C Nmr

A new type of rhenium(I) tricarbonyl porphycene complex is reported based on a reaction between free-base 2,3,6,7,12,13,16,17-octaethylporphycene (H2OEPc) and Re(CO)5Cl . As is the case with tetraphenylporphyrin (TPP), a complex containing only one Re(CO)3 groups, which retains a pyrrole proton, can be isolated and characterized in addition to a bis- Re(I) complex. The ReI(HOEPc)(CO)3 complex was characterized by 1H NMR, 13C NMR, MS, IR, UV-visible, and MCD spectroscopy and cyclic voltammetry. A single crystal was successfully obtained, which enabled the determination of the X-ray structure.

A novel low symmetry sulfur containing porphyrazine: synthesis and its interaction with serum albumin

2003 ◽  
Vol 07 (06) ◽  
pp. 420-425
Author(s):  
Lifen Yang ◽  
Zhenping Ji ◽  
Zhenghe Peng ◽  
Gongzhen Cheng
Keyword(s):  
Serum Albumin ◽  
Organic Solvents ◽  
Binding Sites ◽  
Visible Spectra ◽  
Uv Visible ◽  
Sulfur Containing ◽  
Low Symmetry

A novel low symmetry sulfur-containing porphyrazine, 5,23,28,32-octabutoxy-10,11,17,18-tetrahydro-[9,12,16,19]-tetrathiino-33H, 35H-dinaphtho-porphyrazine (OTTDP), was synthesized by mixed condensation and characterized by NMR, FAB-MS and UV-visible spectra; this complex was found to be low aggregation in organic solvents and can interact with the serum albumin at several binding sites.

Infrared and UV-visible spectra of layer semiconductors Gas, GaSe and GaTe

1977 ◽  
Vol 38 (10) ◽  
pp. 1293-1299 ◽  
Author(s):  
U. Giorgianni ◽  
G. Mondio ◽  
P. Perillo ◽  
G. Saitta ◽  
G. Vermiglio
Keyword(s):  
Visible Spectra ◽  
Uv Visible

ChemInform Abstract: Comparison of Variable-Temperature 1H NMR Spectra of Five-Coordinate High-Spin (S = 5/2) Iron(III) Porphyrins and Chlorins

ChemInform ◽  
1988 ◽  
Vol 19 (36) ◽  
Author(s):  
M. J. PAWLIK ◽  
P. K. MILLER ◽  
E. P. JUN. SULLIVAN ◽  
M. A. LEVSTIK ◽  
D. A. ALMOND ◽  
...  
Keyword(s):  
1H Nmr ◽  
High Spin ◽  
Nmr Spectra ◽  
Variable Temperature ◽  
1H Nmr Spectra

Effect of NO2 substitution and solvent on UV-visible spectra, redox potentials and electron transfer mechanisms of copper β-nitrotriarylcorroles. Proposed electrogeneration of a Cu(I) oxidation state

2016 ◽  
Vol 20 (07) ◽  
pp. 753-765 ◽  
Author(s):  
Lina Ye ◽  
Zhongping Ou ◽  
Yuanyuan Fang ◽  
Yang Song ◽  
Bihong Li ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Soret Band ◽  
Redox Potentials ◽  
Nonaqueous Media ◽  
Initial Assignment ◽  
Visible Spectra ◽  
Phenyl Rings ◽  
Uv Visible ◽  
Electron Reduction ◽  
Transfer Mechanisms

Three copper triarylcorroles containing a [Formula: see text]-pyrrole nitro substituent were synthesized and characterized as to their spectral and electrochemical properties in nonaqueous media. The examined compounds are represented as [Formula: see text]-NO2(YPh)3CorCu, where Cor is the trianion of a triphenylcorrole and Y is a Cl, H or CH3 substituent at the para-position of the three meso-phenyl rings of the compound. The data from absorption spectra, electrochemistry and thin-layer spectroelectrochemistry are consistent with an initial assignment of Cu[Formula: see text]-Cor[Formula: see text] in CH2Cl2, DMF and pyridine and electrogeneration of a formal Cu(II) corrole with an unreduced macrocycle, represented as Cu[Formula: see text]-Cor[Formula: see text], after the first one-electron reduction in these solvents. The doubly reduced [Formula: see text]-nitrocorrole has a sharp Soret band at 439 nm and a well-defined Q-band at 611 nm in CH2Cl2. Similar absorption spectra are seen for the three examined doubly reduced nitrocorroles in DMF and pyridine, suggesting formation of a Cu(I) species with an unreduced macrocycle which is represented as Cu[Formula: see text]-Cor[Formula: see text]. Changes in redox potentials and absorption spectra of the nitrocorroles are examined as a function of solvent and substituents on the meso-phenyl rings of the compounds and comparisons are made between spectral and electrochemical data of the newly synthesized corroles and that of structurally related tetraarylcorroles lacking a [Formula: see text]-nitro group.

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