A Joint Experimental and Computational Investigation on Homoconjugated Push‐Pull Chromophores Derived from 7,7‐Diphenylnorbornane

Herrero-García, Noelia; Heras, María del Rosario Colorado; Torres, María; Fernández, Israel; Barcina, José Osío

doi:10.1002/ejoc.201200159

Cited by 6 publications

(5 citation statements)

References 83 publications

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“…The electron withdrawing functional group at the termination site will lead to the main ligand attracting electrons from the metal center and hence acting to delocalize the electron density. 31 This delocalization will lead to a larger effective conjugation length and hence a bathochromic shift for the absorption features. 32 The variation from a linear trend would suggest the influence of the terminal group as a means of moderating the effect of the auxiliary ligand change.…”

Section: ■ Resultsmentioning

confidence: 99%

“…The largest variation with the systematic variation of the auxiliary ligand is for the FPIP series, closely followed by the CPIP and the NPIP series. The electron withdrawing functional group at the termination site will lead to the main ligand attracting electrons from the metal center and hence acting to delocalize the electron density . This delocalization will lead to a larger effective conjugation length and hence a bathochromic shift for the absorption features .…”

Section: Resultsmentioning

confidence: 99%

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Influence of Auxiliary Ligands on the Photophysical Characteristics of a Series of Ruthenium(II)–Polypyridyl Complexes

O’Neill¹,

Perdisatt²,

O’Connor³

2012

J. Phys. Chem. A

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A series of ruthenium−polypyridyl complexes were studied using UV/vis absorption and luminescence spectroscopy as well as luminescence lifetime determination by time-correlated single photon counting (TCSPC). The complexes were characterized with regard to the variation in the electronic band gap as a result of the sequential variation of the auxiliary ligand 2,2′-bipyridine (bpy), 1,10phenanthroline (phen), and 2,2′-biquinoline (biq) ligands while the main ligand remained constant for three different main ligand types. Luminescence yields were calculated and correlated with structural and electronic variation. It was found that both the absorption and emission characteristics could be tailored through the systematic variation of the reduction potential of the individual auxiliary ligand. This was shown to be the case regardless of the functional group at the end of the main ligand. Stokes shift and Raman spectroscopy were employed as a means to gauge the effect of ligand change on the conjugation and vibrational characteristics of the complexes. Luminescence yield and lifetimes were also shown to be well-defined with regards to systematic structure variations. The well-defined trends established elucidate the effect which variation of auxiliary ligands has on the electronic and excited state characteristics of the ruthenium−polypyridyl systems. These well-defined relationships can potentially be extended to optimize luminescence yield and lifetimes and therefore suitability of such compounds for the application in for example photodynamic therapy.

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Section: ■ Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Influence of Auxiliary Ligands on the Photophysical Characteristics of a Series of Ruthenium(II)–Polypyridyl Complexes

O’Neill¹,

Perdisatt²,

O’Connor³

2012

J. Phys. Chem. A

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“…Homoconjugation can be dened as the orbital overlap of two p-systems separated by a non-conjugated group such as CH 2 (IUPAC). [1][2][3][4][5] This is an interesting theoretical postulate and has been actually conrmed in some systems [6][7][8] but provokes controversy in other systems. 9 While electronic delocalization of homoconjugated alkenes is well established in cationic homoaromatic compounds, the situation in neutral molecules remains unsettled even in homoaromatic compounds.…”

Section: Introductionmentioning

confidence: 99%

“…Homoconjugation may be used to create novel conjugated p-systems but its potential has not been fully explored. 7,8 Porphyrin is one of the most used molecular building block elements for utilization as various functional molecular photonic devices such as articial light harvesting antennas, electric molecular wires, and dye-sensitized solar cells. 10,11 In this perspective, tremendous efforts to synthesize functional porphyrin-based molecular assemblies have been made over the past few decades because of a variety of fascinating characteristics of porphyrin unit; intense electronic absorption and uorescence, rigid structures, tunable optical and redox properties, and photochemical stability.…”

Section: Introductionmentioning

confidence: 99%

Homoconjugation in diporphyrins: excitonic behaviors in singly and doubly linked Zn(ii)porphyrin dimers

et al. 2013

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We have comparatively investigated excitonic features between singly and doubly alkyl bridged Zn(II) porphyrin dimers (SLZn and DLZn, respectively) with Zn(II)tetraphenylporphyrin (ZnTPP) as a reference by using various time-resolved anisotropy measurements. Time-resolved fluorescence anisotropy decay of the B-state of ZnTPP in toluene showed ultrafast dephasing times of 83 and 185 fs with an initial anisotropy value (r 0 ) of $0.7 being consistent with the theoretically proposed one. On the other hand, the Q-state of ZnTPP exhibited a depolarization time of 120 fs with a smaller r 0 of 0.25 than that of the B-state because of probing photo-induced absorption in transient absorption anisotropy measurements. Spectroscopic features in absorption, fluorescence, and excitation anisotropy spectra of SLZn are similar to those of ZnTPP indicating a relatively weak exciton coupling in the Q-state. As a result, the observed depolarization time with a time-constant of 1.4 ps can be explained by a Förster-type incoherent energy transfer process between two constituent subunits. When compared to ZnTPP and SLZn however, DLZn exhibited very different optical characteristics such as more red-shifted absorption and emission spectra, three times larger fluorescence excitation anisotropy values, and ultrafast sign inversion in transient absorption anisotropy. According to these results, it can be inferred that the overall p-electron densities of the electronic excited states in DLZn are fully delocalized in a whole dimer and that DLZn can be regarded as a coherently coupled single quantum system not as separate individual chromophores. Frontier p-molecular orbital structures as well as electron density difference maps between occupied and unoccupied molecular orbitals involved in the electron promotions for underlying excited states clearly represent weakly and strongly exciton-coupled natures of SLZn and DLZn, respectively.Accordingly, the extended conjugation of p-electrons over the whole DLZn molecule demonstrates an example for homoconjugation between two aromatic porphyrins.

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“…The various types of electronic interactions that are inherent to the intervening medium between the donor and the acceptor can be described as resulting from e.g. linear p-conjugation, 4,6 s-interactions, 7 homoconjugation, 8 and foldamer coupling in helical bridges. 9 Photoinduced charge transfer in donor-acceptor substituted compounds with a branched (bifurcated) p-spacer has however received little attention.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced charge transport over branched conjugation pathways: donor–acceptor substituted 1,1-diphenylethene and 2,3-diphenylbutadiene

Walree

Wiel

Williams

2013

Phys. Chem. Chem. Phys.

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Photoinduced charge transport in 1,1-diphenylethene and 2,3-diphenylbutadiene functionalized with an electron donating dimethylamino group and an electron accepting cyano group is reported. UV-spectroscopy reveals that in these compounds, which incorporate a cross-conjugated spacer, a direct charge transfer transition is possible. It is shown by application of the generalized Mulliken-Hush approach that introduction of an additional branching point in the π-electron spacer (i.e., when going from the 1,1-diphenylethene to the 2,3-diphenylbutadiene) leads to only a moderate reduction (68-92%) of the electronic coupling between the ground and the charge separated state. The σ-electron system is however likely to be dominant in the photoinduced charge separation process.

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A Joint Experimental and Computational Investigation on Homoconjugated Push‐Pull Chromophores Derived from 7,7‐Diphenylnorbornane

Cited by 6 publications

References 83 publications

Influence of Auxiliary Ligands on the Photophysical Characteristics of a Series of Ruthenium(II)–Polypyridyl Complexes

Influence of Auxiliary Ligands on the Photophysical Characteristics of a Series of Ruthenium(II)–Polypyridyl Complexes

Homoconjugation in diporphyrins: excitonic behaviors in singly and doubly linked Zn(ii)porphyrin dimers

Photoinduced charge transport over branched conjugation pathways: donor–acceptor substituted 1,1-diphenylethene and 2,3-diphenylbutadiene

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