A drastic substituent effect on the emission properties of quinone diimine models and valuable insight into the excited states of emeraldine

Abdelhameed, Mohammed; Langlois, Adam; Fortin, Daniel; Karsenti, Paul‐Ludovic; Harvey, Pierre D.

doi:10.1039/c4cc05178e

Cited by 9 publications

(25 citation statements)

References 35 publications

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“…The azophenine dye 1 contains both the needed imine and amine linkages. The biggest curiosity in the scarcely reported photophysical properties of the uncycled azophenine chromophore, is the recently reported on–off switching of emission properties of by changing the dihedral angle made by the central quinone diimine ( Q ) plane and the N‐C 6 H 4 one upon the removal of the Boc group in 2 to form 3 a (Figure ; that is, 2 → 3 a ; Boc→H; large angle→small angle) . Despite of this rather interesting phenomena, no explanation was offered at that time.…”

Section: Introductionmentioning

confidence: 73%

“…Because the interconversion requires the rotation of two phenyl groups either at once or sequentially, the process may be slow at room temperature but should be completely frozen down at 77 K. Consequently, the presence of two emission lifetimes for a seemingly single emission band and for a symmetric azophenine containing four identical arms can only be explained by their presence. Indeed, this was the case for compound 3 a . TDDFT compute quasi‐identical simulated spectra for isomorphs 1 and 2 for compounds 1 and 3 a (cf.…”

Section: Resultsmentioning

confidence: 99%

“…The target polyads are prepared according to pathways shown in Schemes and . B 4 Q (Scheme ) proceeds from compound 3 a . After the deprotection of the ethynyl linkers, compound 4 is obtained.…”

Section: Resultsmentioning

confidence: 99%

“…This phenomenon has been fully described by Lindsey and collaborators . For compound 3 a , the two transient components (1.2 and 4.4 ps) reproduce well the previously reported data (1.1 and 4.9 ps) for the same compound …”

Section: Resultsmentioning

confidence: 99%

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Azophenine as Central Core for Efficient Light Harvesting Devices

Karsenti

Harvey

2018

ChemPhysChem

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The notoriously non-luminescent uncycled azophenine (Q) was harnessed with Bodipy and zinc(II)porphyrin antennas to probe its fluorescence properties, its ability to act as a singlet excited state energy acceptor and to mediate the transfer. Two near-IR emissions are depicted from time-resolved fluorescence spectroscopy, which are most likely due to the presence of tautomers of very similar calculated total energies (350 cm ; DFT; B3LYP). The rates for energy transfer, k (S ), for Bodipy*→Q are in the order of 10 -10 s and are surprisingly fast when considering the low absorptivity properties of the lowest energy charge transfer excited state of azophenine. The rational is provided by the calculated frontier molecular orbitals (MOs) which show atomic contributions in the C H C≡CC H arms, thus favoring the double electron exchange mechanism. In the mixed-antenna Bodipy-porphyrin star molecule, the rate for Bodipy*→porphyrin has also been evaluated (≈16×10 s ) and is among the fastest rates reported for Bodipy-zinc(II)porphyrin pairs. This astonishing result is again explained from the atomic contributions of the C H C≡CC H and C≡CC H arms thus favouring the Dexter process. Here, for the first time, this process is found to be sensitively temperature-dependent. The azophenine turns out to be excellent for electronic communication.

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Section: Introductionmentioning

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Azophenine as Central Core for Efficient Light Harvesting Devices

Karsenti

Harvey

2018

ChemPhysChem

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“…The synthon 42 was relevant to study the excited state of an emeraldine model and has later been used for the preparation of luminescent azophenine-Pt organometallic complexes [99].Scheme 10. Preparation of DABQDI from p-benzoquinone[98].…”

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confidence: 99%

Benzoquinonediimine ligands: Synthesis, coordination chemistry and properties

Pascal

Siri

2017

Coordination Chemistry Reviews

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This review covers the synthesis and properties of 2,5-diamino-1,4-benzoquinonediimines (DABQDI), and their use as ligand in coordination chemistry. Although reported more than a century ago, these molecules emerged as highly versatile ligands only from 1998, and are so far used for the synthesis of numerous complexes with remarkable properties. This exceptional versatility results from the possible tuning of the N-substituents and the observation of an isomerization process upon coordination depending on the metal center. As such, these DABQDI can be also considered as ligands that combine the structural elements of ortho-and para-benzoquinonediimines (o-BQDI and p-BQDI) which are bidentate monotopic and monodentate ditopic ligands, respectively. These two classes of BQDI ligands are also reviewed in order to parallel their properties to those of the complexes based on DABQDI.

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Platinum Complexes of N,N′,N″,N‴-Diboronazophenines

Aly

Karsenti

et al. 2017

Inorg. Chem.

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Azophenine, (α-CHNH)(CH-N═CH═N-CH), well known to be non-emissive, was rigidified by replacing two amine protons by two difluoroboranes (BF) and further functionalized at the para-positions of the phenyl groups by luminescent trans-ArC≡C-Pt(PR)-C≡C ([Pt]) arms [Ar = CH (R = Et), hexa(n-hexyl)truxene) (Tru; R = Bu)]. Two effects are reported. First, the linking of these [Pt] arms with the central azophenine (CH-N═CH(NH)═N-CH; Q) generates very low energy charge-transfer (CT) singlet and triplet excited states (([Pt]-to-Q)*) with absorption bands extending all the way to 800 nm. Second, the rigidification of azophenine by the incorporation of BF units renders the low-lying CT singlet state clearly emissive at 298 and 77 K in the near-IR region. DFT computations place the triplet emission in the 1200-1400 nm range, but no phosphorescence was detected. The photophysical properties are investigated, and circumstantial evidence for slow triplet energy transfers, Tru* → Q, is provided.

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A drastic substituent effect on the emission properties of quinone diimine models and valuable insight into the excited states of emeraldine

Cited by 9 publications

References 35 publications

Azophenine as Central Core for Efficient Light Harvesting Devices

Azophenine as Central Core for Efficient Light Harvesting Devices

Benzoquinonediimine ligands: Synthesis, coordination chemistry and properties

Platinum Complexes of N,N′,N″,N‴-Diboronazophenines

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