Electronic Interactions Between Polycyclic Arenes in Cyclophanes

Haenel, Matthias W.; Schweitzer, Dieter

doi:10.1021/ba-1988-0217.ch019

Cited by 14 publications

(13 citation statements)

References 32 publications

(82 reference statements)

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“…The reduction in the D value is expected to increase with the extent of aromatic stacking interactions involving the peptide chromophore on the basis of previous studies of Lys-Trp-Lys complex formation with poly(dT) (Maki & Cha, 1983). The size of the -AD values exhibited by the quinoline chromophores of the 2QNpolynucleotide complexes is of the same order of magnitude as those previously reported for stacking interactions between Trp residues and nucleoide bases in the binding of E. coli single-stranded DNA binding proteins and poly(dT) (Khamis et al, 1987) and those measured for cyclophanes in which naphthalene rings (approximately 3.1 Á apart) are forced into stacking arrangements by out-of-plane methylene bridges (Haenel & Schweitzer, 1988). Both proximity and orientation of the interacting ring systems were found to influence the magnitude of the reduction of the zfs D parameter of the phanes relative to their monomeric units.…”

Section: Discussionsupporting

confidence: 83%

Optically detected triplet-state magnetic resonance studies of the DNA complexes of the bisquinoline analog of echinomycin

Alfredson¹,

Maki²,

Waring³

1991

Biochemistry

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The polymeric DNA and model duplex oligonucleotide complexes of the bisquinoline analogue of echinomycin (2QN) have been studied by optical detection of triplet-state magnetic resonance (ODMR) spectroscopy, with the quinoline chromophores of the drug used as intrinsic probes. Plots of ODMR transition frequencies versus monitored wavelength revealed heterogeneity in the phosphorescence emission of 2QN which was ascribed to the presence of a major and minor conformation of the drug in aqueous solutions (referred to as the red and blue forms of 2QN, respectively, in this report). ODMR results, in conjunction with findings from low-temperature phosphorescence investigations, indicate that the quinoline chromophores of the major (red) form of 2QN are involved in aromatic stacking interactions in complexes with the natural DNAs from Escherichia coli, Micrococcus lysodeikticus, Clostridium perfringens, and calf thymus as evidenced by red shifts in the phosphorescence 0,0-band of the drug, reductions in the phosphorescence lifetime and zero-field splitting (zfs) D and E parameters, and polarity reversals of the ODMR slow passage signals upon complex formation between the analogue and DNA. The polarity reversals, which reflect shifts in the triplet-state sublevel populations induced by complex formation, apparently result from changes in the triplet sublevel decay constants upon binding to the natural DNAs. The 2QN complexes of the double-stranded alternating copolymers poly(dG-dC).poly(dG-dC) [abbreviated as poly[d(G-C)2]] and poly(dA-dT).poly(dA-dT) [abbreviated as poly(dA-dT).poly(dA-dT) [abbreviated as poly[d(A-T)2], the homopolymer duplexes poly(dG).poly(dC) [abbreviated as poly(dG.dC)] and poly(dA).poly(dT) [abbreviated as poly(dA.dT)], and the self-complementary oligonucleotides d(ACGT)2, d(TCGA)2, and d(ACGTACGT)2 were also investigated. The extent of reduction of the zfs D parameter (delta D) for the major form of 2QN upon complex formation with the polymeric DNAs was found to scale linearly with the standard free energy of the drug-DNA interaction (delta G degrees) calculated from previously reported binding studies for these targets [Fox, K. R., et al. (1980) Biochem. J. 191, 729-740]. This relationship between spectroscopic and thermodynamic properties of the 2QN-polynucleotide complexes is a consequence of the effects of base stacking interactions on the electronic states of the intercalator, which were postulated to arise from second-order shifts of the ground-state and the triplet-state energies of the complex on the basis of a modification of the solvent effect theory of van Egmond et al. [(1975) Chem. Phys. Lett. 34, 423-426].

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Section: Discussionsupporting

confidence: 83%

Optically detected triplet-state magnetic resonance studies of the DNA complexes of the bisquinoline analog of echinomycin

Alfredson¹,

Maki²,

Waring³

1991

Biochemistry

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“…The π−π* transition bands of [ n . n ]naphthalenophanes with different types of linkages show a variety of spectral patterns depending on the stacking mode of the naphthyl groups …”

Section: Resultsmentioning

confidence: 99%

“…n ]paracyclophanes with n = 1−3 show three π−π* transition bands in the spectral range 245−320 nm, in contrast to acyclic para-substituted benzene derivatives which show a single electronic band with vibrational structure in this spectral range. − This abnormality of the spectra arises from the proximity of the two phenyl groups and the distortion of the phenyl rings, and it decreases with increasing length of the bridges between the phenyl groups; − the spectra of paracyclophanes with n ≥ 4 are practically identical with those of acyclic p -dialkylbenzenes. Systematic studies of various types of macrocycles containing two aromatic groups in the ring systems have shown that the spectral properties are sensitive to the stacking mode of the aromatic systems . Cyclophanes that have donor groups in the ring systems undergo ring contraction upon coordination with metal ions .…”

Section: Introductionmentioning

confidence: 99%

Binuclear Copper(II) Chelates of Amide-Based Cyclophanes

et al. 1998

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A chelating cyclophane has been synthesized by cyclocondensation of two ethylenediaminetetraacetic (EDTA) units with two p-phenylenediamine units: the resulting cyclophane is 2,9,18,25-tetraoxo-4,7,20,23-tetrakis(carboxymethyl)-1,4,7,10,17,20,23,26-octaaza[10.10]paracyclophane, abbreviated as (bis-edtapdn)H(4). Cyclocondensation of two EDTA and two 1,5-diaminonaphthalene units has given the naphthalenophane, 2,9,22,29-tetraoxo-4,7,24,27-tetrakis(carboxymethyl)-1,4,7,10,21,24,27,30-octaaza[10.10](1,5)naphthalenophane, (bis-edtanap)H(4). Studies of electronic and EPR spectra have been carried out on the binuclear Cu(2+) complexes of these new ligands and of related chelating cyclophanes, 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza[10.1.10.1]paracyclophane, abbreviated as (bis-edtabpm)H(4), and 2,9,25,32-tetraoxo-4,7,27,30-tetrakis(carboxymethyl)-1,4,7,10,24,27,30,33-octaaza-17,40-dioxa[10.1.10.1]paracyclophane, abbreviated as (bis-edtabpe)H(4). Common features of these chelating cyclophanes are as follows: (1) amino, amide, and pendant carboxymethyl donor groups are substituents in the cyclophane ring, and (2) the amide groups are directly bound to the aromatic groups. These ligands formed neutral binuclear Cu(2+) chelates [Cu(2)L](0) that are water-insoluble. In alkaline solutions, these Cu(2+) complexes were converted to anionic chelates [Cu(2)(LH(-)(4))](4)(-) in which deprotonated amide nitrogens coordinated Cu(2+) ions. These anionic metal chelates of (bis-edtapdn)H(4), (bis-edtabpm)H(4), and (bis-edtabpe)H(4) exhibited three pi-pi transition bands in the spectral range 240-340 nm, in contrast to the uncoordinated cyclophanes, which showed a single band in this spectral range. The unusual pi-pi transition spectra of the [Cu(2)(LH(-)(4))](4)(-) complexes originate from the combined effect of metal-ligand charge transfer and proximity of the pi systems. The absorption and emission spectra of (bis-edtanap)H(4) were also influenced by coordination with copper. The EPR spectrum of [Cu(2)(bis-edtanapH(-)(4))](4)(-) in a methanol glass matrix showed a hyperfine structure due to the spin exchange between two Cu(2+) ions. These unusual spectral and magnetic properties arise from the strong coordination between Cu(2+) ions and deprotonated amide nitrogens that are bound to the pi systems.

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“…The latter emission exhibits the vibrational fine structures similar to that of neutral 1 , revealing the local nature of the transition associated with the anthracene chromophore. The relative red‐shift observed for neutral 1 is attributed to the CT character of the transition involving the nitrogen's nonbonding orbital, which is missing in protonated 1‐H + . The excitation spectrum for the low‐energy transition was essentially superimposable with the UV‐vis spectrum of 1‐H + (Figure S6 in the Supporting Information), and the band was assigned to the emission from the CT state.…”

Section: Resultsmentioning

confidence: 54%

“…Pyridinophane 1 was readily protonated in the presence of fluoroboric acid to produce DA cyclophane 1‐H + . A number of cyclophanes containing anthracene unit(s) have been reported in the literature, most of which focused on the fluorescence and photochemical behaviors, while anthracenophanes with DA interaction have rarely been prepared . Naturally, a strong DA interaction, which is electrostatic in nature, is expected to occur between the anthracene and pyridinium moieties in 1‐H + .…”

Section: Introductionmentioning

confidence: 99%

Chiroptical properties of dithia[3.3]cyclophanes composed of anthracene and pyridine/pyridinium moieties: A combined experimental and theoretical study

et al. 2017

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Circular dichroisms (CDs) of neutral and protonated [3.3]anthracenopyridinophane (1 and 1-H ) were investigated experimentally and theoretically. Introducing an anthracene moiety with extended conjugation affected the cyclophane structure with the bent angles being appreciably reduced from those of parent [3.3]pyridinophane. The Cotton effects (CEs) observed at the B band for both 1 and 1-H were fairly strong and apparently bisignate, which, however, turned out not to be a simple exciton couplet but to be composed of multiple transitions. In contrast, the CEs were much weaker in the L band region. The spectral changes upon protonation were less significant compared with the parent pyridinophane, being dominated by the local transitions of anthracene. Nevertheless, the CD spectra of 1 and 1-H were well reproduced by theoretical calculations to allow us an unambiguous absolute configuration determination of the first high-performance liquid chromatography (HPLC) elute (from Chiralcel IB column) as S . The transannular interactions between the anthracene and pyridine/pyridinium units were examined by UV-vis and fluorescence spectroscopy to reveal a charge-transfer (CT) band in the low-energy region, particularly for 1-H . Despite the comparable CT interactions, the CE at the CT band was much stronger for the anthracenopyridinophane than for the parent pyridinophane, affording an anisotropy (g) factor as large as 4 × 10 .

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Electronic Interactions Between Polycyclic Arenes in Cyclophanes

Cited by 14 publications

References 32 publications

Optically detected triplet-state magnetic resonance studies of the DNA complexes of the bisquinoline analog of echinomycin

Optically detected triplet-state magnetic resonance studies of the DNA complexes of the bisquinoline analog of echinomycin

Binuclear Copper(II) Chelates of Amide-Based Cyclophanes

Chiroptical properties of dithia[3.3]cyclophanes composed of anthracene and pyridine/pyridinium moieties: A combined experimental and theoretical study

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