[n]Cyclo-para-biphenylmethine Polyradicaloids: [n]Annulene Analogs and Unusual Valence Tautomerization

Ni, Yong; Sandoval‐Salinas, María Eugenia; Tanaka, Takayuki; Phan, Hoa; Herng, Tun Seng; Gopalakrishna, Tullimilli Y.; Ding, Jun; Osuka, Atsuhiro; Casanova, David; Wu, Jishan

doi:10.1016/j.chempr.2018.09.025

Cited by 27 publications

(30 citation statements)

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“…Interestingly, the series of [n]CPBM-Ant (n = 3 − 6) compounds is predicted to increase their radical character as a function of their increasing size, in perfect agreement with experimental and RAS-SF results. 53 Following the agreement found between N F OD values at the FT-TPSS and RAS-SF levels, see also Table S1, we represent in Figure 3 Energy difference between low-and high-spin states.…”

Section: Resultssupporting

confidence: 60%

Investigating the (Poly)Radicaloid Nature of Real-World Organic Compounds with DFT-Based Methods

et al. 2020

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Recent advances in the synthesis of stable organic (open-shell) polyradicaloids have opened their application as active compounds for emerging technologies. These systems typically exhibit small energy differences between states with different spin multiplicities, which are intrinsically difficult to calculate by theoretical methods. We thus apply here some DFT-based variants (FT-DFT, SF-DFT, and SF-TDDFT) on a test set of large and real-world molecules, as test systems for which such energy differences are experimentally available, also comparing systematically with RAS-SF results to infer if shortcomings of previous DFT applications are corrected. Additionally, we explore the spin-spin contribution to the ZFS tensor, of high interest for EPR spectroscopy, and derive the spatial extent of the corresponding (photoexcited) triplet state.

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Section: Resultssupporting

confidence: 60%

Investigating the (Poly)Radicaloid Nature of Real-World Organic Compounds with DFT-Based Methods

et al. 2020

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“…N F OD represents thus the integrated number of strongly correlated electrons and is equivalent to the widely used N U metrics introduced by Head-Gordon, 64 obtained from Natural Orbital Occupation Numbers (NOONs) and extensively applied to characterize a radical-like character of real-world compounds. [65][66][67][68][69] Table 1 gathers the FT-DFT calculated N F OD values for all the considered compounds, and for both S 0 and T 1 states (note that S 1 is not directly available by applying the FT-DFT method). We can observe how the N F OD values roughly increases from [2]triangulene (2T) to [4]triangulene (4T), and for both states, with N F OD (T 1 ) > N F OD (S 0 ) specially true for 4T systems.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Negative Singlet–Triplet Excitation Energy Gap in Triangle-Shaped Molecular Emitters for Efficient Triplet Harvesting

et al. 2021

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The full harvesting of both singlet and triplet excitons can pave the way towards more efficient molecular light-emission mechanisms (i.e., TADF or Thermally Activated Delayed Fluorescence) beyond the spin statistics limit. This TADF mechanism benefits from low (but typically positive) singlet-triplet energy gaps or ∆E ST . Recent research has suggested the possibility of inverting the order of the energy of lowest singlet and triplet excited-states, thus opening new pathways to foster light emission without any energy barrier through triplet to singlet conversion, which is systematically investigated here by means of theoretical methods. To this end, we have selected a set of heteroatom-substituted triangle-shaped molecules (or triangulenes) for which ∆E ST < 0 is predicted. We successfully rationalize the origin of that energy inversion, and the reasons for which theoretical methods might produce qualitatively inconsistent predictions depending on how they treat n-tuple excitations (e.g., the large contribution of double excitations for all the ground-and excited-states involved). Unfortunately, the TD-DFT method is unable to deal with the physical effects driving this behaviour, which prompted us to the use here of more sophisticated ab initio methods such as SA-CASSCF, SC-NEVPT2, SCS-CC2, and SCS-ADC(2).

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“…The implementation of RASCI ansatz within effective algorithms, such as analytical integral evaluation [28,57] and the resolution-of-identity approximation (RI) [58] resulted in effective computer codes capable of handling extended systems, such as carbon nanotubes [59] and organic macrocycles. [41,42,60]…”

Section: The Rasci Methodsmentioning

confidence: 99%

Calculation of Spin–orbit Couplings Using RASCI Spinless One-Particle Density Matrices: Theory and Applications

Carreras¹,

Jiang²,

Pokhilko³

et al. 2020

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<div> <div> <div> <p>This work presents the formalism and implementation for calculations of spin–orbit couplings (SOCs) within the Breit–Pauli (BP) Hamiltonian using zero-order (non- relativistic) wave-functions described by the restricted active space configuration in- teraction (RASCI) method with general excitation operators: excitation energies, spin- flip, ionization potential, and electron attachment. The implementation is based on the application of Wigner–Eckart’s theorem within the spin space, which allows the computation of the entire SOC matrix based on the explicit calculation of just one tran- sition between the two spin-multiplets. Numeric results for a diverse set of atoms and molecules highlight the importance of balanced treatment of correlation and adequate basis sets, and illustrate overall robust performance of RASCI SOCs. The new imple- mentation is a useful addition to a methodological toolkit for studying spin-forbidden processes. </p> </div> </div> </div>

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[n]Cyclo-para-biphenylmethine Polyradicaloids: [n]Annulene Analogs and Unusual Valence Tautomerization

Cited by 27 publications

References 58 publications

Investigating the (Poly)Radicaloid Nature of Real-World Organic Compounds with DFT-Based Methods

Investigating the (Poly)Radicaloid Nature of Real-World Organic Compounds with DFT-Based Methods

Negative Singlet–Triplet Excitation Energy Gap in Triangle-Shaped Molecular Emitters for Efficient Triplet Harvesting

Calculation of Spin–orbit Couplings Using RASCI Spinless One-Particle Density Matrices: Theory and Applications

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