Potential Use of Squarates and Croconates as Singlet Fission Sensitizers

López‐Carballeira, Diego; Casanova, David; Ruipérez, Fernando

doi:10.1002/cphc.201800329

Cited by 14 publications

(10 citation statements)

References 105 publications

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“…Cyclic oxocarbon acids, such as squaric acid (H 2 C 4 O 4 , 3,4-dihydroxycyclobut-3-ene-1,2-dione), are of interest because of their cyclic structures, aromatic nature, wide-ranging chemical and physical properties leading to a variety of materials applications, , and varying coordination modes in coordination and structural studies. − These varying coordination modes (variable denticities and bridging abilities) are attractive for the potential to produce novel extended networks. Squarate was chosen as a ligand of interest here because of its unique coordination modes and the fact that its aromatic/delocalized bonding makes the oxo donors of the ligand “softer” (under the Pearson definition) than would otherwise be expected.…”

Section: Introductionmentioning

confidence: 99%

Trivalent f-Element Squarates, Squarate-Oxalates, and Cationic Materials, and the Determination of the Nine-Coordinate Ionic Radius of Cf(III)

et al. 2020

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The synthesis, structure, and solid-state UV–vis–NIR spectroscopy of four new f-element squarates, M2(C4O4)3(H2O)4 (M = Eu, Am, Cf) and Sm(C4O4)(C4O3OH)(H2O)2·0.5H2O, four new cationic lanthanide squarate chlorides, [M4(C4O4)5(H2O)12]Cl2·5H2O (M = Eu, Dy, Ho Er), and two new actinide squarate oxalates, M2(C4O4)2(C2O4)(H2O)4 (M = Am, Cf), are presented. All of the metal centers are trivalent. Single-crystal X-ray diffraction analysis reveals that M2(C4O4)3(H2O)4 and Sm(C4O4)(C4O3OH)(H2O)2·0.5H2O have a two-dimensional sheet structure constructed from MO7(H2O)2 monocapped square-antiprismatic (coordination number (CN) = 9) metal centers and SmO6(H2O)2 square-antiprismatic (CN = 8) metal centers, respectively, whereas M2(C4O4)2(C2O4)(H2O)4 have a three-dimensional (3D) structure constructed from MO7(H2O)2 monocapped square-antiprismatic (CN = 9) metal centers. Additionally, the cationic framework materials [M4(C4O4)5(H2O)12]Cl2·5H2O have a 3D structure constructed from two crystallographically unique MO5(H2O)3 square-antiprismatic (CN = 8) metal centers. In these structures, the squarate ligands bind to the metal centers with varying coordination modes and denticities. The results of this study provide another example of the nonparallel chemistry between the lanthanides and transplutonium elements. From the crystallographic data for the isotypic series M2(C4O4)3(H2O)4 (M = La–Nd, Sm, Eu) and the linear regression fit to a plot of the unit cell volume as a function of the cube of the ionic radius, the nine-coordinate ionic radius of Cf 3+ was determined to be 1.127 ± 0.003 Å. Finally, computational analysis of the americium and californium complexes M2(C4O4)3(H2O)4 and M2(C4O4)2(C2O4)(H2O)4 reveals three important attributes: (i) the 5f orbitals are nonbonding in all cases, with the bonding differences occurring with the empty 6d orbitals; (ii) the Cf complexes exhibit more covalent character than their Am counterparts; and (iii) there is more covalent character in the squarate-oxalate complexes than in the squarate complexes.

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Section: Introductionmentioning

confidence: 99%

Trivalent f-Element Squarates, Squarate-Oxalates, and Cationic Materials, and the Determination of the Nine-Coordinate Ionic Radius of Cf(III)

et al. 2020

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“…Singlet fission (SF) is a photophysical process in which a singlet exciton state (S 1 S 0 , S 0 S 1 ), or a Frenkel exciton (FE) state, is converted into a correlated triplet (double-triplet) exciton state(T 1 T 1 ) (hereafter referred to as TT), which is followed by decoupling and spatial separation into two triplet states. − Although SF was originally reported about 50 years ago, , the interest in SF was revived in 2006, when Hanna and Nozik proposed multiple exciton generation through SF as a way to break the Shockley–Queisser limit on the efficiency of single-junction photovoltaics . Indeed, the explorations for novel SF materials as well as their mechanisms have been conducted intensely both experimentally and theoretically. − ,− …”

Section: Introductionmentioning

confidence: 99%

Breakdown of the Perturbative Approach to Molecular Packing Dependence of Singlet Fission Rates in Pentacene Dimer Models: A Systematic Comparison with the Quantum Master Equation Approach

et al. 2019

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We have compared the molecular packing dependences of singlet fission (SF) rates calculated by perturbative and quantum master equation approaches using slip-stacked pentacene dimer models to clarify the applicability of the perturbative treatment and the importance of vibronic coupling effects on the SF dynamics. Several significant differences between these two approaches are found in the peak positions as well as in the relative peak amplitudes on the two-dimensional map of the SF rate as a function of the longitudinal and lateral displacements of the molecular backbones. Using the relative relaxation factor analysis, these disagreements are more striking for increasing the electronic couplings between the related diabatic exciton states as well as for reducing the energy difference between the lowest adiabatic Frenkel-like and double-triplet-like exciton states to match the primary vibronic coupling frequency. These results systematically illuminate the breakdown of the perturbative approach to the prediction of SF rates and indicate that exciton dynamics with explicit vibronic coupling is indispensable for obtaining a quantitative molecular packing dependence of SF rates.

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“…This report describes an advance in our work on croconaine dyes, an emerging near‐infrared chromophore system that is gaining increasing attention for various sensing, photothermal, optoelectronic, and photoacoustic applications . In 2013, we showed that croconaine dyes, such as C1 (Scheme ), are very useful as near‐infrared photothermal agents, and in the subsequent time period we and others have shown that they can be used for clean photothermal heating of nanoparticles without producing singlet oxygen, photothermal switching of polymer morphology,, and laser ablation of tumors in living animals , .…”

Section: Introductionmentioning

confidence: 99%

“…gaining increasing attention for various sensing, photothermal, optoelectronic, and photoacoustic applications. [15][16][17][18] In 2013, we showed that croconaine dyes, such as C1 (Scheme 1), are very useful as near-infrared photothermal agents, [14] and in the subsequent time period we and others have shown that they can be used for clean photothermal heating of nanoparticles without producing singlet oxygen, [19] photothermal switching of polymer morphology, [20,21] and laser ablation of tumors in living animals. [22,23] We have also shown that croconaines can be converted to rotaxane structures, such as 1, that exhibit sharp absorption bands at 820 nm, even under conditions that aggregate the molecules.…”

Section: Introductionmentioning

confidence: 99%

Croconaine Rotaxane Dye with 984 nm Absorption: Wavelength‐Selective Photothermal Heating

et al. 2019

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Croconaines are an emerging class of near‐infrared dyes that are useful for various sensing, photothermal, optoelectronic, and photoacoustic applications. Previous work encapsulated a dumbbell‐shaped croconaine dye whose structure contains two thiophene flanking units inside a tetralactam macrocycle and produced a croconaine rotaxane 1 with a narrow 824 nm absorption band. Herein, a new rotaxane 2 is reported that encapsulates a croconaine dye with two thienothiophene flanking units. The new croconaine rotaxane 2 exhibits a narrow 984 nm absorption band that is distinct from the 824 nm absorption of rotaxane 1. Photothermal heating experiments showed that an 830 nm diode laser selectively heats a solution containing rotaxane 1, with no heating of a solution containing rotaxane 2. Conversely, a 980 nm diode laser selectively heats a solution containing rotaxane 2, with no heating of a solution containing rotaxane 1. The new croconaine rotaxane 2 shows no fatigue after four cycles of laser heating and cooling.

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Potential Use of Squarates and Croconates as Singlet Fission Sensitizers

Cited by 14 publications

References 105 publications

Trivalent f-Element Squarates, Squarate-Oxalates, and Cationic Materials, and the Determination of the Nine-Coordinate Ionic Radius of Cf(III)

Trivalent f-Element Squarates, Squarate-Oxalates, and Cationic Materials, and the Determination of the Nine-Coordinate Ionic Radius of Cf(III)

Breakdown of the Perturbative Approach to Molecular Packing Dependence of Singlet Fission Rates in Pentacene Dimer Models: A Systematic Comparison with the Quantum Master Equation Approach

Croconaine Rotaxane Dye with 984 nm Absorption: Wavelength‐Selective Photothermal Heating

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