The Radical Anion of 2,7‐Diazapyrene, a Change in Orbital Sequence on Protonation

Bruhin, J.; Gerson, Fabian

doi:10.1002/hlca.19750580822

Cited by 12 publications

(3 citation statements)

References 19 publications

(9 reference statements)

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“…Part). The ESR spectrum of the photogenerated product gave a signal (g = 2.0022, a(N(2), N (7)) % 4.48 G, a(CH3N(2),CH3N(7)) = 4.38 G) in agreement with that reported for the Me,DAP" radical cation in MeOH (a(N(2),N(7)) = 4.70 G, a(CH,N(2),CH3N(7)) = 4.39 G) [43], although the resonance lines were broader and the hyperfine coupling with the aromatic protons (1.83 and 0.40 G) [43] was not resolved (Fig. 4 ) .…”

supporting

confidence: 92%

Molecular Anion Binding and Substrate Photooxidation in Visible Light by 2,7‐Diazapyrenium Cations

Blacker¹,

Jaźwiński²,

Lehn³

1987

Helvetica Chimica Acta

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The 2,7-diazapyrenium group (DAP2+) combines the features of pyrene, of methylviologen, and of nucleicacid intercalators and may thus present a variety of interesting properties. The cations 1 and 2 and the bis-diazapyrenium species 3 have been synthesized and shown to bind molecular anions like aromatic polycarboxylates, giving rise to pronounced shifts of 'H-NMR signals, modifications of UVjVIS absorption spectra, and quenching of fluorescence. The complexes formed probably have a face-to-face structure, and their stability constants are remarkably high, in particular for the bis-diazapyrenium cation 3 which is susceptible to form intercalative chelate complexes such as 9 (log K, B 3 for 1, up to ca. 7 or more for 3a). Neutral molecules like adenine are also bound, but much less strongly. Visible-light irradiation of Me,DAP2+ (1) in presence of various electron donors, such as EDTA, gives the reduced species Me2DAP+' wich has been characterized by UVjVIS and ESR spectroscopy. The results indicate that Me2DAP2+ (1) functions as a methylviologen analogue, photoactive in visible light. Thus 2,7-diazapyrenium cations are attractive subunits for incorporation into macropolycyclic structures to give photoand electroactive receptor molecules.

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supporting

confidence: 92%

Molecular Anion Binding and Substrate Photooxidation in Visible Light by 2,7‐Diazapyrenium Cations

Blacker¹,

Jaźwiński²,

Lehn³

1987

Helvetica Chimica Acta

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“…To gain insight into the nature of interactions and binding geometry of aza-aromatic compounds with DNA, we have conducted a spectroscopic and calorimetric study of 2,7-diazapyrene (DAP) and its two cationic homologues N -methyl-2,7-diazapyrenium monocation (MDAP) and N,N ‘-dimethyl-2,7-diazapyrenium dication (DMDAP) (Figure ). The parent compound DAP has been the subject of both spectroscopic − and electrochemical − investigations, and its electronic properties are well understood. The DNA interactions with DMDAP have previously been studied in electron-transfer − and photocleavage experiments.…”

Section: Introductionmentioning

confidence: 99%

DNA Binding Properties of 2,7-Diazapyrene and Its N-Methylated Cations Studied by Linear and Circular Dichroism Spectroscopy and Calorimetry

Becker

Nordén

1997

J. Am. Chem. Soc.

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The binding of 2,7-diazapyrene (DAP), N-methyl-2,7-diazapyrenium monocation (MDAP), and N,N′dimethyl-2,7-diazapyrenium dication (DMDAP) to calf thymus DNA has been studied with respect to molecular geometry and thermodynamics. It is concluded from flow linear dichroism (LD) and induced circular dichroism (CD) spectra that the three diazapyrenes bind by intercalation to alternating AT as well as GC polynucleotide duplexes, as indicated by strong interactions with the transitions of the nucleobases in conjunction with approximately perpendicular orientations of the in-plane symmetry axes relative to the DNA helix axis. The reduced LD (LD r ) LD/A iso ) of the DNA complexes is characterized by marked fine structure, decreasing in the order DAP > MDAP > DMDAP. This finding is interpreted in terms of a microscopic heterogeneity associated with rotational mobility of the ligand in a tilted intercalation pocket, with the dication DMDAP having less rotational freedom than the neutral DAP has. Other distinct differences between the three diazapyrenes are revealed in their thermodynamic parameters of binding. DAP binds with a negative ∆H°(-9 kcal/mol) and a negative ∆S°(-7 cal/(mol K)), whereas the binding of the dication DMDAP is entropically driven (+43 cal/(mol K)) but enthalpically disfavored (+5.2 kcal/mol), the monocation MDAP having an intermediate position (∆H°) -3 kcal/mol, ∆S°) +12 cal/(mol K)).

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“…As to be expected 21Box, being a derivative of the strongly basic benzimidazole, is the system most difficult to reduce. The influence of the heteroatoms in [19][20][21] reflects that in the six-membered heterocycles l f, 15 and 16.…”

Section: Five-membered Heterocyclesmentioning

confidence: 99%

Two step reversible redox systems of the weitz type

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The Radical Anion of 2,7‐Diazapyrene, a Change in Orbital Sequence on Protonation

Abstract: Summavy.ESR.-spectra are reported for the radical anion I -8 of 2,7-diazapyrene (I), along with those for the radical cations I(2H) -@ and I(2CH3) -@ of 2.7-dihydro-2,7-diazapyrenc and 1) Universitat Basel.

Cited by 12 publications

References 19 publications

Molecular Anion Binding and Substrate Photooxidation in Visible Light by 2,7‐Diazapyrenium Cations

Molecular Anion Binding and Substrate Photooxidation in Visible Light by 2,7‐Diazapyrenium Cations

DNA Binding Properties of 2,7-Diazapyrene and Its N-Methylated Cations Studied by Linear and Circular Dichroism Spectroscopy and Calorimetry

Two step reversible redox systems of the weitz type

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