Carbazole‐Terpyridine Donor‐Acceptor Dyads with Rigid π‐Conjugated Bridges

Matteucci, Elia; Baschieri, Andrea; Sambri, Letizia; Monti, Fiorella; Pavoni, Eleonora; Bandini, Elisa; Armaroli, Nicola

doi:10.1002/cplu.201900213

Cited by 11 publications

(4 citation statements)

References 80 publications

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“…While this wavelength dependence can unmask dual emission, C-Zero only shows one band using 300 to 425 nm excitation (Supporting Information). In TICT compounds, those with pretwisted ground states tend to suppress the LE state; yet, this character does not help explain the observations suggesting that the LE state is inactive in C-Zero and that it more closely resembles other types of CT fluorophores. − …”

Section: Results and Discussionmentioning

confidence: 98%

Zero-Overlap Fluorophores for Fluorescent Studies at Any Concentration

et al. 2020

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Fluorophores are powerful tools for the study of chemistry, biology, and physics. However, fluorescence is severely impaired when concentrations climb above 5 μM as a result of effects like self-absorption and chromatic shifts in the emitted light. Herein, we report the creation of a charge-transfer (CT) fluorophore and the discovery that its emission color seen at low concentrations is unchanged even at 5 mM, some 3 orders of magnitude beyond typical limits. The fluorophore is composed of a triphenylamine-substituted cyanostar macrocycle, and it exhibits a remarkable Stokes shift of 15 000 cm–1 to generate emission at 633 nm. Crucial to the performance of this fluorophore is the observation that its emission spectrum shows near-zero overlap with the absorption band at 325 nm. We propose that reducing the spectral overlap to zero is a key to achieving full fluorescence across all concentrations. The triphenylamine donor and five cyanostilbene acceptor units of the macrocycle generate an emissive CT state. Unlike closely related donor–acceptor control compounds showing dual emission, the cyanostar framework inhibited emission from the second state to create a zero-overlap fluorophore. We demonstrated the use of emission spectroscopy for characterization of host–guest complexation at millimolar concentrations, which are typically the exclusive domain of NMR spectroscopy. The binding of the PF6 – anion generates a 2:1 sandwich complex with blue-shifted emission. Distinct from twisted intramolecular charge-transfer (TICT) states, experiment-supported density functional theory shows a 67° twist inside an acceptor unit in the CT state instead of displaying a twist between the donor and acceptor; it is TICT-like. Inspired by the findings, we uncovered similar concentration-independent behavior from a control compound, strongly suggesting this behavior may be latent to other large Stokes-shift fluorophores. We discuss strategies capable of generating zero-overlap fluorophores to enable accurate fluorescence characterization of processes across all practical concentrations.

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Section: Results and Discussionmentioning

confidence: 98%

Zero-Overlap Fluorophores for Fluorescent Studies at Any Concentration

et al. 2020

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“…51 The electron rich functional triarylamine unit with thienylphenyl (D) has been judiciously chosen to access its extended p-conjugation and tunable ICT (intramolecular charge transfer) emission in the visible region. [55][56][57] Furthermore, the propeller geometry of the triphenylamine moiety will induce steric hindrance preventing its molecular packing in solid state. This will have an advantageous effect to gain enhanced emission of the conjugated chromophore in solid state.…”

Section: Resultsmentioning

confidence: 99%

Design and synthesis of a push–pull arylene–vinylene terpyridyl conjugate: multifunctional behaviors exhibited by a single molecule

et al. 2022

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A multifunctional D-π-A push-pull arylene-vinylene conjugated terpyridine, 4'-(4-{2-[4-[bis(4-thiophen-2-yl-phenyl)amino]phenyl-ethenyl}phenyl)-2,2':6',2''-terpyridine has been designed and successfully developed. Photophysical properties was systematically explored showing tunable multifunctional behaviors including solvatochromism, vapochromism, piezofluorochromism and remarkable chemosensing...

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“…The intra- and intermolecular charge transfer mechanisms are mainly considered for systems with conjugated D-A molecules, which is the case of the unimer U , where the central N -phenylcarbazole unit (Cbz) is an electron donor to the tpy end-groups. Thus, the U molecule is an A-D-A type system [ 57 , 58 , 59 ]. The applied slow and controlled PVD deposition process of U molecules onto substrates enables their energetically favored packing to supramolecular structures with reduced interplanar distances.…”

Section: Discussionmentioning

confidence: 99%

Synapse-Mimicking Memristors Based on 3,6-Di(tpy)-9-Phenylcarbazole Unimer and Its Copolymer with Cobalt(II) Ions

Pandey,

Chernyshev,

Panthi

et al. 2024

Polymers

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The title compound, unimer U (tpy stands for 2,2′:6′,2″-terpyridin-4′-yl end-group), by itself shows the memristor effect with a retention time of 18 h and persistence of 11 h. Its coordination copolymer with Co(II) ions, [CoU]n, exhibits multimodal resistance changes similar to the synaptic responses observed in biological systems. More than 320 cycles of potentiation and depression measured in continuous sequence occurred without observing a significant current change, confirming the operational stability and reproducibility of the device based on the [CoU]n polymer. The synaptic effect of a device with an indium tin oxide (ITO)/[CoU]n/top-electrode (TE) configuration is more pronounced for the device with TE = Au compared to devices with TE = Al or Ga. However, the latter TEs provide a cost-effective approach without any significant compromise in device plasticity. The detected changes in the synaptic weight, about 12% for pair-pulse facilitation and 80% for its depression, together with a millisecond trigger and reading pulses that decay exponentially on the time scale typical of neurosynapses, justify the device’s ability to learn and memorize. These properties offer potential applications in neuromorphic computation and brain-inspired synaptic devices.

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Carbazole‐Terpyridine Donor‐Acceptor Dyads with Rigid π‐Conjugated Bridges

Cited by 11 publications

References 80 publications

Zero-Overlap Fluorophores for Fluorescent Studies at Any Concentration

Zero-Overlap Fluorophores for Fluorescent Studies at Any Concentration

Design and synthesis of a push–pull arylene–vinylene terpyridyl conjugate: multifunctional behaviors exhibited by a single molecule

Synapse-Mimicking Memristors Based on 3,6-Di(tpy)-9-Phenylcarbazole Unimer and Its Copolymer with Cobalt(II) Ions

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