scholarly journals Hydricity, electrochemistry, and excited-state chemistry of Ir complexes for CO2 reduction

2017 ◽  
Vol 198 ◽  
pp. 301-317 ◽  
Author(s):  
Gerald F. Manbeck ◽  
Komal Garg ◽  
Tomoe Shimoda ◽  
David J. Szalda ◽  
Mehmed Z. Ertem ◽  
...  
Keyword(s):  
Excited State ◽  
Dft Calculations ◽  
Density Functional ◽  
Reduction Potential ◽  
Co2 Reduction ◽  
Theoretical Data ◽  
Functional Theory ◽  
State Reduction ◽  
State Potential ◽  
Derivatives Of

We prepared electron-rich derivatives of [Ir(tpy)(ppy)Cl]+ with modification of the bidentate (ppy) or tridentate (tpy) ligands in an attempt to increase the reactivity for CO2 reduction and the ability to transfer hydrides (hydricity). Density functional theory (DFT) calculations reveal that complexes with dimethyl-substituted ppy have similar hydricities to the non-substituted parent complex, and photocatalytic CO2 reduction studies show selective CO formation. Substitution of tpy by bis(benzimidazole)-phenyl or -pyridine (L3 and L4, respectively) induces changes in the physical properties that are much more pronounced than from the addition of methyl groups to ppy. Theoretical data predict [Ir(L3)(ppy)(H)] as the strongest hydride donor among complexes studied in this work, but [Ir(L3)(ppy)(NCCH3)]+ cannot be reduced photochemically because the excited state reduction potential is only 0.52 V due to the negative ground state potential of −1.91 V. The excited state of [Ir(L4)(ppy)(NCCH3)]2+ is the strongest oxidant among complexes studied in this work and the singly-reduced species is formed readily upon photolysis in the presence of tertiary amines. Both [Ir(L3)(ppy)(NCCH3)]+ and [Ir(L4)(ppy)(NCCH3)]2+ exhibit electrocatalytic current for CO2 reduction. While a significantly greater overpotential is needed for the L3 complex, a small amount of formate (5–10%) generation in addition to CO was observed as predicted by the DFT calculations.

Lowest Energy Structures and Electronic Properties of Small Molybdenum Clusters

2005 ◽  
Vol 494 ◽  
pp. 79-82 ◽  
Author(s):  
V. Koteski ◽  
Bozidar Cekić ◽  
N. Novaković ◽  
J. Belošević-Čavor
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Electronic Properties ◽  
First Principles ◽  
Cluster Size ◽  
Density Functional ◽  
Theoretical Data ◽  
Binding Energies ◽  
Functional Theory ◽  
Average Bond

The structural and geometric properties of small Mo clusters are studied by means of first principles density functional theory (DFT) calculations with planewaves and pseudopotentials. The lowest energy structures of Mon (n=2-6) clusters are determined. The evolution of electronic properties with increasing cluster size is discussed. The geometric structure, average bond lengths, and binding energies of the lowest energy isomers are reported and the results are compared with the available experimental and theoretical data.

New design strategy for chemically-stable blue phosphorescent materials: improving the energy gap between the T1 and 3MC states

2021 ◽  
Vol 23 (5) ◽  
pp. 3543-3551
Author(s):  
Sunwoo Kang ◽  
Taekyung Kim ◽  
Jin Yong Lee
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Dft Calculations ◽  
Chemical Stability ◽  
Density Functional ◽  
Energy Gap ◽  
Design Strategy ◽  
Functional Theory ◽  
Blue Phosphorescent

A series of Ir- and Pt-based blue phosphorescent materials were theoretically investigated by means of density functional theory (DFT) calculations to improve their chemical stability in the excited state.

scholarly journals The Photochemistry of Fe2(S2C3H6)(CO)6(µ-CO) and Its Oxidized Form, Two Simple [FeFe]-Hydrogenase CO-Inhibited Models. A DFT and TDDFT Investigation

Inorganics ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 16
Author(s):  
Federica Arrigoni ◽  
Giuseppe Zampella ◽  
Luca De Gioia ◽  
Claudio Greco ◽  
Luca Bertini
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Temperature Dependent ◽  
Cationic Form ◽  
Functional Theory ◽  
Co Dissociation ◽  
State Potential ◽  
Energy Surfaces

FeIFeI Fe2(S2C3H6)(CO)6(µ-CO) (1a–CO) and its FeIFeII cationic species (2a+–CO) are the simplest model of the CO-inhibited [FeFe] hydrogenase active site, which is known to undergo CO photolysis within a temperature-dependent process whose products and mechanism are still a matter of debate. Using density functional theory (DFT) and time-dependent density functional theory (TDDFT) computations, the ground state and low-lying excited-state potential energy surfaces (PESs) of 1a–CO and 2a+–CO have been explored aimed at elucidating the dynamics of the CO photolysis yielding Fe2(S2C3H6)(CO)6 (1a) and [Fe2(S2C3H6)(CO)6]+ (2a+), two simple models of the catalytic site of the enzyme. Two main results came out from these investigations. First, a–CO and 2a+–CO are both bound with respect to any CO dissociation with the lowest free energy barriers around 10 kcal mol−1, suggesting that at least 2a+–CO may be synthesized. Second, focusing on the cationic form, we found at least two clear excited-state channels along the PESs of 2a+–CO that are unbound with respect to equatorial CO dissociation.

scholarly journals The Photochemistry of Fe2(S2C3H6)(CO)6(µ-CO) and its Oxidized Form, Two Simple [FeFe]-Hydrogenase CO-Inhibited Models. A DFT and TDDFT Investigation

2021 ◽  
Author(s):  
Federica Arrigoni ◽  
Giuseppe Zampella ◽  
Luca De Gioia ◽  
Claudio Greco ◽  
Luca Bertini
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Temperature Dependent ◽  
Cationic Form ◽  
Functional Theory ◽  
Co Dissociation ◽  
State Potential ◽  
Energy Surfaces

FeIFeI Fe2(S2C3H6)(CO)6(µ-CO) (1a-CO) and its FeIFeII cationic species (2a+-CO) are the simplest model of the CO-inhibited [FeFe] hydrogenase active site, which is known to undergo CO photolysis within a temperature- dependent process whose products and mechanism are still a matter of debate. Using Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) computations, the ground state and low-lying excited state potential energy surfaces (PESs) of 1a-CO and 2a+-CO have been explored aimed at elucidating the dynamics of the CO photolysis yielding Fe2(S2C3H6)(CO)6 (1a) and Fe2(S2C3H6)(CO)6+ (2a+), two simple models of the catalytic site of the enzyme. Two main results came out from these investigations. First, a-CO and 2a+-CO are both bound with respect to any CO dissociation with lowest free energy barriers around 10 kcal mol-1, suggesting that at least 2a+-CO might be synthetized. Second, focusing on the cationic form, we found at least two clear excited state channels along the PESs of 2a+-CO that are unbound with respect to equatorial CO dissociation.

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