1
|
Effect of crystal packing on charge transfer in the heteroleptic gallium(III) complex. Russ Chem Bull 2023. [DOI: 10.1007/s11172-023-3724-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
|
2
|
Charge Transfer Chromophores Derived from 3d-Row Transition Metal Complexes. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238175. [PMID: 36500270 PMCID: PMC9736222 DOI: 10.3390/molecules27238175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/18/2022] [Accepted: 11/20/2022] [Indexed: 11/25/2022]
Abstract
A series of new charge transfer (CT) chromophores of "α-diimine-MII-catecholate" type (where M is 3d-row transition metals-Cu, Ni, Co) were derived from 4,4'-di-tert-butyl-2,2'-bipyridyl and 3,6-di-tert-butyl-o-benzoquinone (3,6-DTBQ) in accordance with three modified synthetic approaches, which provide high yields of products. A square-planar molecular structure is inherent for monomeric [CuII(3,6-Cat)(bipytBu)]∙THF (1) and NiII(3,6-Cat)(bipytBu) (2) chromophores, while dimeric complex [CoII(3,6-Cat)(bipytBu)]2∙toluene (3) units two substantially distorted heteroleptic D-MII-A (where D, M, A are donor, metal and acceptor, respectively) parts through a donation of oxygen atoms from catecholate dianions. Chromophores 1-3 undergo an effective photoinduced intramolecular charge transfer (λ = 500-715 nm, extinction coefficient up to 104 M-1·cm-1) with a concomitant generation of a less polar excited species, the energy of which is a finely sensitive towards solvent polarity, ensuring a pronounced negative solvatochromic effect. Special attention was paid to energetic characteristics for CT and interacting HOMO/LUMO orbitals that were explored by a synergy of UV-vis-NIR spectroscopy, cyclic voltammetry, and DFT study. The current work sheds light on the dependence of CT peculiarities on the nature of metal centers from various groups of the periodic law. Moreover, the "α-diimine-MII-catecholate" CT chromophores on the base of "late" transition elements with differences in d-level's electronic structure were compared for the first time.
Collapse
|
3
|
London HC, Pritchett DY, Pienkos JA, McMillen CD, Whittemore TJ, Bready CJ, Myers AR, Vieira NC, Harold S, Shields GC, Wagenknecht PS. Photochemistry and Photophysics of Charge-Transfer Excited States in Emissive d10/ d0 Heterobimetallic Titanocene Tweezer Complexes. Inorg Chem 2022; 61:10986-10998. [PMID: 35786924 DOI: 10.1021/acs.inorgchem.2c01746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Transition-metal complexes that undergo ligand-to-metal charge transfer (LMCT) to d0 metals are of interest as possible photocatalysts due to the lack of deactivating d-d states. Herein, the synthesis and characterization of nine titanocene complexes of the formula Cp2Ti(C2Ar)2·MX (where Ar = phenyl, dimethylaniline, or triphenylamine; and MX = CuCl, CuBr, or AgCl) are presented. Solid-state structural characterization demonstrates that MX coordinates to the alkyne tweezers and CuX coordination has a greater structural impact than AgCl. All complexes, including the parent complexes without coordinated MX, are brightly emissive at 77 K (emission max between 575 and 767 nm), with the coordination of MX redshifting the emission in all cases except for the coordination of AgCl into Cp2Ti(C2Ph)2. TDDFT investigations suggest that emission is dominated by arylalkynyl-to-titanium 3LMCT in all cases except Cp2Ti(C2Ph)2·CuBr, which is dominated by CuBr-to-Ti charge transfer. In room-temperature fluid solution, only Cp2Ti(C2Ph)2 and Cp2Ti(C2Ph)2·AgCl are emissive, albeit with photoluminescent quantum yields ≤2 × 10-4. The parent complexes photodecompose in room-temperature solution with quantum yields, Φrxn, between 0.25 and 0.99. The coordination of MX decreases Φrxn by two to three orders of magnitude. There is a clear trend that Φrxn increases as the emission energy increases. This trend is consistent with a competition between energy-gap-law controlled nonradiative decay and thermally activated intersystem crossing between the 3LMCT state and the singlet transition state for decomposition.
Collapse
Affiliation(s)
- Henry C London
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - David Y Pritchett
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Jared A Pienkos
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Colin D McMillen
- Department of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - Thomas J Whittemore
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Conor J Bready
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Alexis R Myers
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Noah C Vieira
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Shannon Harold
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - George C Shields
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| | - Paul S Wagenknecht
- Department of Chemistry, Furman University, Greenville, South Carolina 29609, United States
| |
Collapse
|
4
|
Schindler K, Zobi F. Anticancer and Antibiotic Rhenium Tri- and Dicarbonyl Complexes: Current Research and Future Perspectives. Molecules 2022; 27:539. [PMID: 35056856 PMCID: PMC8777860 DOI: 10.3390/molecules27020539] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/23/2021] [Accepted: 01/12/2022] [Indexed: 12/20/2022] Open
Abstract
Organometallic compounds are increasingly recognized as promising anticancer and antibiotic drug candidates. Among the transition metal ions investigated for these purposes, rhenium occupies a special role. Its tri- and dicarbonyl complexes, in particular, attract continuous attention due to their relative ease of preparation, stability and unique photophysical and luminescent properties that allow the combination of diagnostic and therapeutic purposes, thereby permitting, e.g., molecules to be tracked within cells. In this review, we discuss the anticancer and antibiotic properties of rhenium tri- and dicarbonyl complexes described in the last seven years, mainly in terms of their structural variations and in vitro efficacy. Given the abundant literature available, the focus is initially directed on tricarbonyl complexes of rhenium. Dicarbonyl species of the metal ion, which are slowly gaining momentum, are discussed in the second part in terms of future perspective for the possible developments in the field.
Collapse
Affiliation(s)
| | - Fabio Zobi
- Department of Chemistry, Fribourg University, Chemin du Musée 9, 1700 Fribourg, Switzerland;
| |
Collapse
|
5
|
Wells KA, Yarnell JE, Sheykhi S, Palmer JR, Yonemoto DT, Joyce R, Garakyaraghi S, Castellano FN. Accessing the triplet manifold of naphthalene benzimidazole-phenanthroline in rhenium(I) bichromophores. Dalton Trans 2021; 50:13086-13095. [PMID: 34581368 DOI: 10.1039/d1dt02329b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The steady-state and ultrafast to supra-nanosecond excited state dynamics of fac-[Re(NBI-phen)(CO)3(L)](PF6) (NBI-phen = 16H-benzo[4',5']isoquinolino[2',1':1,2]imidazo[4,5-f][1,10]phenanthrolin-16-one) as well as their respective models of the general molecular formula [Re(phen)(CO)3(L)](PF6) (L = PPh3 and CH3CN) has been investigated using transient absorption and time-gated photoluminescence spectroscopy. The NBI-phen containing molecules exhibited enhanced visible light absorption with respect to their models and a rapid formation (<6 ns) of the triplet ligand-centred (LC) excited state of the organic ligand, NBI-phen. These triplet states exhibit an extended excited state lifetime that enable the energized molecules to readily engage in triplet-triplet annihilation photochemistry.
Collapse
Affiliation(s)
- Kaylee A Wells
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA.
| | - James E Yarnell
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA. .,Department of Chemistry & Chemistry Research Center, United States Air Force Academy, Colorado Springs, Colorado, 80840-6230, USA
| | - Sara Sheykhi
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA.
| | - Jonathan R Palmer
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA.
| | - Daniel T Yonemoto
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA.
| | - Rosalynd Joyce
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA.
| | - Sofia Garakyaraghi
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA.
| | - Felix N Castellano
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695-8204, USA.
| |
Collapse
|
6
|
Pashanova KI, Bitkina VO, Yakushev IA, Arsenyev MV, Piskunov AV. Square-Planar Heteroleptic Complexes of α-Diimine-Ni II-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer. Molecules 2021; 26:4622. [PMID: 34361775 PMCID: PMC8347615 DOI: 10.3390/molecules26154622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/05/2022] Open
Abstract
Two heteroleptic NiII complexes combined the redox-active catecholate and 2,2'- bipyridine ligand platforms were synthesized to observe a photoinduced intramolecular ligand-to-ligand charge transfer (LL'CT, HOMOcatecholate → LUMOα-diimine). A molecular design of compound [NiII(3,6-Cat)(bipy)]∙CH3CN (1) on the base of bulky 3,6-di-tert-butyl-o-benzoquinone (3,6-DTBQ) was an annelation of the ligand with an electron donor glycol fragment, producing derivative [NiII(3,6-Catgly)(bipy)]∙CH2Cl2 (2), in order to influence the energy of LL'CT transition. A substantial longwave shift of the absorption peak was observed in the UV-Vis-NIR spectra of 2 compared with those in 1. In addition, the studied NiII derivatives demonstrated a pronounced negative solvatochromism, which was established using a broad set of solvents. The molecular geometry of both compounds can be ascribed as an insignificantly distorted square-planar type, and the π-π intermolecular stacking of the neighboring α-diimines is realized in a crystal packing. There is a lamellar crystal structure for complex 1, whereas the perpendicular T-motifs with the inter-stacks attractive π-π interactions form the packing of complex 2. The redox-active nature of ligand systems was clearly shown through the electrochemical study: a quasi-reversible one-electron reduction of 2,2'-bipyridine and two reversible successive one-electron oxidative conversations ("catecholate dianion-o-benzosemiquinonato radical anion-neutral o-benzoquinone") were detected.
Collapse
Affiliation(s)
- Kira I. Pashanova
- Laboratory of Metal Complexes with Redox-Active Ligands, G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 Tropinina Street, 603137 Nizhny Novgorod, Russia; (K.I.P.); (V.O.B.); (M.V.A.)
| | - Vladlena O. Bitkina
- Laboratory of Metal Complexes with Redox-Active Ligands, G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 Tropinina Street, 603137 Nizhny Novgorod, Russia; (K.I.P.); (V.O.B.); (M.V.A.)
| | - Ilya A. Yakushev
- N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninski Prospect, 119991 Moscow, Russia;
| | - Maxim V. Arsenyev
- Laboratory of Metal Complexes with Redox-Active Ligands, G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, 49 Tropinina Street, 603137 Nizhny Novgorod, Russia; (K.I.P.); (V.O.B.); (M.V.A.)
| | - Alexandr V. Piskunov
- N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninski Prospect, 119991 Moscow, Russia;
| |
Collapse
|
7
|
Fernández-Terán RJ, Sévery L. Coordination Environment Prevents Access to Intraligand Charge-Transfer States through Remote Substitution in Rhenium(I) Terpyridinedicarbonyl Complexes. Inorg Chem 2021; 60:1325-1333. [PMID: 33301310 DOI: 10.1021/acs.inorgchem.0c02914] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Six rhenium(I) κ3N-dicarbonyl complexes with 4'-(4-substituted phenyl)terpyridine ligands were evaluated in their ground and excited states. These complexes, bearing substituents of different electron-donating strengths-from CN to NMe2-were studied by a combination of transient IR (TRIR), electrochemistry, and IR spectroelectrochemistry, as well as time-dependent density functional theory (TD-DFT). They exhibit panchromatic absorption and can act as stronger photoreductants than their tricarbonyl counterparts. The ground- and excited-state potentials, absorption maxima, and lifetimes (250-750 ps) of these complexes correlate well with the Hammett σp substituent constants, showing the systematic effect of remote substitution in the ligand framework. TRIR spectroscopy allowed us to assign the lowest singlet and triplet excited states to a metal-to-ligand charge-transfer (MLCT) character. This result contrasts our previous report on analogous κ2N-tricarbonyl complexes, where remote substitution switched the character from MLCT to intraligand charge transfer. With the help of TD-DFT calculations, we dissect the geometric and electronic effects of coordination of the third pyridine, local symmetries, and increasing conjugation length. These results give valuable insights for the design of complexes with long-lived triplet excited states and enhanced absorption throughout the visible spectrum, while showcasing the boundaries of the excited-state switching strategy via remote substitution.
Collapse
Affiliation(s)
| | - Laurent Sévery
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| |
Collapse
|
8
|
Shakirova JR, Nayeri S, Jamali S, Porsev VV, Gurzhiy VV, Levin OV, Koshevoy IO, Tunik SP. Targeted Synthesis of NIR Luminescent Rhenium Diimine cis,trans-[Re( N N )(CO) 2 (L) 2 ] n+ Complexes Containing N-Donor Axial Ligands: Photophysical, Electrochemical, and Theoretical Studies. Chempluschem 2020; 85:2518-2527. [PMID: 33226192 DOI: 10.1002/cplu.202000597] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/05/2020] [Indexed: 11/09/2022]
Abstract
The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re( N N )(CO)3 (NCMe)]OTf ( N N =phenantroline and neocuproine) afforded cis,trans-Re( N N )(CO)2 (NCMe)2 ]+ acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4'-bipyridine, N-methyl-4,4'-bipyridine) gave a novel family of the diimine cis,trans-[Re( N N )(CO)2 (L)2 ]+ complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from 711 to 805 nm. The nature of emissive excited states was studied using DFT calculations to show dominant contribution of 3 MLCT (dπ(Re)→π*( N N )) character. Electrochemical (CV and DPV) studies of the monocationic diimine complexes revealed one reduction and one oxidation wave assigned to reduction of the diimine moiety and oxidation of the rhenium center, respectively.
Collapse
Affiliation(s)
- J R Shakirova
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - S Nayeri
- Department of Chemistry, Sharif University of Technology, P.O. Box, 11155-3516, Tehran, Iran
| | - S Jamali
- Department of Chemistry, Sharif University of Technology, P.O. Box, 11155-3516, Tehran, Iran
| | - Vitaly V Porsev
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - Vladislav V Gurzhiy
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - Oleg V Levin
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - I O Koshevoy
- Department of Chemistry, University of Eastern Finland, 80101, Joensuu, Finland
| | - S P Tunik
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| |
Collapse
|