Interfacial Electron Transfer Dynamics of Two Newly Synthesized Catecholate Bound Ru<sup>II</sup> Polypyridyl‐Based Sensitizers on TiO<sub>2</sub> Nanoparticle Surface – A Femtosecond Pump Probe Spectroscopic Study

Banerjee, Tanmay; Rawalekar, Sachin; Das, Amitava; Ghosh, Hirendra N.

doi:10.1002/ejic.201100411

Cited by 26 publications

(23 citation statements)

References 85 publications

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“…From the absorption spectrum with TiO 2 , the configuration of the absorption spectrum is similar to the original spectrum of 2 ( Figure 2D). The attachment to TiO 2 led to quenching of emission ( Figure 2E), which is in agreement with literature reports, 31 and indicates that electrons injected from the excited state of 2 to the conduction band of TiO 2 . The TEM image ( Figure 2F) clearly shows the presence of colloidal particle 5 attached to the semiconductor surface.…”

Section: Pt(ii) Complexes As Photosensitizers For Hydrogen Evolutionsupporting

confidence: 92%

New platinum and ruthenium Schiff base complexes for water splitting reactions

Wang

Chen

2015

Dalton Trans.

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New platinum(ii) and ruthenium(ii) mononuclear complexes with naphthalene-based Schiff base ligands L1 (H2-selnaph) and L2 (H2-selnaph-COOH) were synthesized: Pt-selnaph (), Pt-selnaph-COOH (), Ru-selnaph(4-picoline)2 (), and Ru-selnaph(isoquinoline)2 (). The complexes were characterized by NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight spectrometry, and elemental analysis, and their electrochemical and photophysical properties were investigated. The luminescent complexes and were used as photosensitizers for visible-light driven hydrogen production reactions in the presence of sacrificial electron donor triethylamine and cocatalyst precursor K2PtCl4 aqueous solution. When complex was attached to the surface of TiO2 by a carboxyl group, enhanced hydrogen photogeneration was achieved compared with complex alone, with turnover numbers of about 84 after 12 h irradiation. Calculations based on electrochemical and spectroscopic data also confirmed the feasibility of electron injection through the carboxyl group of complex into the conduction band of TiO2 for hydrogen production reactions. Complexes and were found to be efficient stable water oxidation (NH4)2Ce(NO3)6-driven catalysts with a first-order reaction behavior. A turnover frequency of 5.34 min(-1) was achieved for complex , while complex exhibited an enhanced turnover frequency of 11.9 min(-1) in pH 1.0 aqueous solution. Turnover numbers up to 1400 and 2060 were obtained after 6.5 h of reaction for and , respectively. Unique mechanistic information for water splitting is also presented through electrochemical, spectroscopic and ESI-MS high-valent ruthenium-oxo intermediate investigations.

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Section: Pt(ii) Complexes As Photosensitizers For Hydrogen Evolutionsupporting

confidence: 92%

New platinum and ruthenium Schiff base complexes for water splitting reactions

Wang

Chen

2015

Dalton Trans.

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“…Ghosh, Das, and coworkers have investigated in detail the photoexcitation and relaxation kinetics of several catechol-anchored metallo-organic Ru-based dyes [175]. Similar results have been observed recently for Ru II -dyecatecholate complexes with other conjugated electron-donating moieties [182]. Similar results have been observed recently for Ru II -dyecatecholate complexes with other conjugated electron-donating moieties [182].…”

Section: Dye-sensitized Solar Cellssupporting

confidence: 76%

Catechol‐Based Biomimetic Functional Materials and their Applications

Busquè

Sedó

Ruiz‐Molina

et al. 2014

Bio‐ and Bioinspired Nanomaterials

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A prime example of how biomaterials can inspire their fabricated counterparts is the case of catechol-based materials. Catechols are aromatic derivatives with two adjacent (ortho-) hydroxyl groups; they are ubiquitous in nature, taking part in a remarkable range of processes and functions. This functional versatility can be explained considering that catechols can act as weak acids and, simultaneously, as easily oxidizable reducing agents. In addition, the presence of two hydroxyl groups in vicinal positions in the aromatic ring makes them ideal for bidentate coordination and intermolecular interactions.Intense research has been aimed at mimicking the natural roles of catechols by developing new functional materials. This chapter will focus on past and recent studies involving the design, development, and biomimetic use of synthetic molecules and materials with catechols present in their structure, mainly in the fields of biomedicine, analytical, nanotechnology, and materials science, and showing the potential of this chemical functionality to afford promising candidate structures for technologically relevant applications.This chapter is structured considering the main functional roles of the catechol moiety in the molecules and materials fabricated, either as individual molecules or as part of a polymeric backbone. Thus, the three first sections are devoted to cases where catechols act as linkers between: macroscopic surfaces, acting as adhesives (Section 11.2); macroscopic surfaces and functional molecules (Section 11.3); and outer parts of micro-or nanoscopic structures and functional molecules (Section 11.4). Section 11.5 is focused in the role of catechols as constituent blocks of functional 2D or 3D scaffolds and structures. Next, the chelating properties of catechols and their function for metal sequestration are addressed in Section 11.6. Finally, the two last sections are centered on their presence in different sensors (Section 11.7) and electronic devices (Section 11.8), owing to the redox features of the catechol/quinone system.

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“…Our earlier investigations reveal that the transient absorption spectra for complex ‐TiO 2 are mainly due to charge‐separated species (ie. cation radical and injected electron) and the contribution of excited states is negligible . Our group and many other research groups reported that the conduction band electrons can be detected by the characteristic absorption in visible, near‐IR and mid‐IR region …”

Section: Resultsmentioning

confidence: 64%

“…The excited state relaxation processes consist of internal conversion (IC), intersystem crossing (ISC) and vibrational relaxation (VR). Previous studies on transient spectroscopy state that the femtosecond injection is characteristic feature of the nonthermalized 1 MLCT excited state whereas picosecond injection occur via thermalized 3 MLCT excited state . The transient spectra of complexes 1–3 at each time delay show difference positive absorption (▵A) at higher wavelength ∼500‐800 nm along with difference negative absorption (▵A) below 500 nm for ground state bleaching.…”

Section: Resultsmentioning

confidence: 97%

“…Further, we have performed the transient absorption studies of complexes 1–3 in colloidal solution of TiO 2 nanoparticle to explore the interfacial electron transfer dynamics with semiconducting TiO 2 nanoparticle using similar condition as used for their bare complex solution (Figure b, d and f) . Our earlier investigations reveal that the transient absorption spectra for complex ‐TiO 2 are mainly due to charge‐separated species (ie.…”

Section: Resultsmentioning

confidence: 99%

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Ruthenium Bis(terpyridine) Complexes Based on D-P-A Functionalization: Experimental and Theoretical Evidences

2017

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We have synthesized heteroleptic complexes 1–4 with improved photophysical properties efficient for interfacial charge injection to semiconducting TiO2nanoparticle. The complexes show improved optical properties with τavg varying from 7.18 ns to 3.89 ns, which is greater than 0.25 ns for [Ru(tpy)2](PF6)2 and sufficient to perform the interfacial electron transfer study with semiconducting TiO2. The time‐correlated single photon counting (TCSPC) measurement with colloidal TiO2show quenched decay pattern and decreased lifetime. The electrochemical study exhibit the oxidation potential (Eox ) in the range of 1.11‐1.17 V vs Ag/AgCl reference electrode and found to be shifted cathodically compared to 1.32 V for [Ru(tpy)2](PF6)2. This cathodic shift is due to the presence of electron donating group that make the metal centre more prone to oxidation and the related excited state oxidation potential show stronger reductant behavior in MLCT excited state. Also, the transient absorption studies with TiO2 nanoparticle is in good harmony with photoinduced electron injection from LUMO of complexes to the conduction band (CB) of TiO2 as LUMO level of complexes were above the CB of TiO2(‐3.65 eV). Further, the theoretical (TDDFT) data is in good agreement with experimental data.

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Interfacial Electron Transfer Dynamics of Two Newly Synthesized Catecholate Bound Ru^II Polypyridyl‐Based Sensitizers on TiO₂ Nanoparticle Surface – A Femtosecond Pump Probe Spectroscopic Study

Cited by 26 publications

References 85 publications

New platinum and ruthenium Schiff base complexes for water splitting reactions

New platinum and ruthenium Schiff base complexes for water splitting reactions

Catechol‐Based Biomimetic Functional Materials and their Applications

Ruthenium Bis(terpyridine) Complexes Based on D-P-A Functionalization: Experimental and Theoretical Evidences

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Interfacial Electron Transfer Dynamics of Two Newly Synthesized Catecholate Bound RuII Polypyridyl‐Based Sensitizers on TiO2 Nanoparticle Surface – A Femtosecond Pump Probe Spectroscopic Study

Cited by 26 publications

References 85 publications

New platinum and ruthenium Schiff base complexes for water splitting reactions

New platinum and ruthenium Schiff base complexes for water splitting reactions

Catechol‐Based Biomimetic Functional Materials and their Applications

Ruthenium Bis(terpyridine) Complexes Based on D-P-A Functionalization: Experimental and Theoretical Evidences

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Interfacial Electron Transfer Dynamics of Two Newly Synthesized Catecholate Bound Ru^II Polypyridyl‐Based Sensitizers on TiO₂ Nanoparticle Surface – A Femtosecond Pump Probe Spectroscopic Study