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Synthesis and Electrochemical Study of Re(I) and Mo(0)-carbonyl diimine Complexes for Photo- and Electrocatalytic Reduction of CO2
Full text linkSynthesis and Electrochemical Studies of Rhenium(I) and Molybdenum(0) Complexes as Electrocatalysts for Reduction of Carbon Dioxide
Full text linkThe photochemical and electrochemical conversion of CO2 to higher-energy products has been a focus of research as a path to renewable fuels. This thermodynamically unfavorable process can be improved by employing transition-metal coordination compounds which, in the form of molecular or supramolecular organometallic catalysts, are capable of mediating CO2 reduction. Among them, we focused on Rhenium and Molybdenum. However, whereas a wide number of Rhenium(I) carbonyl-diimine complexes showed to be photo/redox active, and has already been successfully tested for the electrocatalytic CO2 reduction, to our knowledge, there are no reports about the use of tetracarbonyl polypyridyl molybdenum(0) complexes as electrocatalysts for the reduction of CO2. In this perspective, some [Mo(CO)4(L)] (L= 2,2’-bipyridine (bpy); 1,10-phenantroline (phen) and similar derivatives) were synthesized and tested for electrochemical reduction of carbon dioxide. Moreover, a series of novel Re(I)-carbonyl diimine complexes has been synthesized and tested for the same purpose. The latter class of compounds is characterized by new polypyridyl ligands, derived from PNI-phen (N-(1,10-phenantroline)-4-(1-piperidinyl)naphthalene-1,8-dicarboximide), which revealed to be able to provide a 3000-fold excited state lifetime enhancement in a Re(I) charge-transfer complex [1]. The electrochemical behavior of both the classes of compounds was compared with the activity of Re(CO)3Cl(bipy) [2].
Quite surprisingly, CV measurements (in MeCN and acetone), performed under both inert and CO2 atmosphere at room temperature, revealed that [Mo(CO)4(2,2’-bipyridyl)] shows redox activity as electrocatalyst for CO2 reduction, although the overpotential at which the process occurs is rather negative (about -1.9 V vs SCE). The catalytic activity was also confirmed by controlled-potential electrolysis at -1.80 V, coupled with gas chromatography (GC)
Recent developments in Group VI and VII transition metal homogeneous catalysts for CO2 electro- and photoreduction
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Synthesis and Electrochemical Study of Re(I) and Mo(0) Complexes with polypiridyl ligands for Photo- and Electrocatalytic Reduction of CO2
Full text linkIn recent years, the photo- and electrochemical conversion of CO2 to higher-energy products has been improved by employing transition metal coordination compounds with polypyridyl ligands (e.g. Ru, Os, Re, Mn [1,2]), in the form of molecular or supramolecular organometallic catalysts. In this perspective, our research has mainly focused on the synthesis of a series of novel Re(I)-carbonyl diimine complexes, to be efficiently used as catalysts in both photo- and electrocatalysis for CO2 reduction. In more detail, this new class of compounds is characterized by the presence of common polypyridyl ligands covalently attached to the highly fluorescent PNI cromophore (N-(diimine)-4-(1- piperidinyl) naphthalene-1,8-dicarboximide), which revealed to be able to provide a huge excited state lifetime enhancement in a Re(I) charge-transfer complex [3]. This feature may play a key role in the process of catalytic CO2 reduction (especially in photocatalysis). The spectroscopic characterization (optical and NMR) of the new samples was followed by the study of their electrochemical behaviour either in inert atmosphere and in presence of CO2, which was finally compared with that of Re(CO)3(bipy)Cl, taken as a reference compound [4]. Photocatalytic measurements are under progress.
On the other hand, looking at a practical use of these systems, the usage of quite abundant first and second row transition metals instead of rare ones is very attractive. For example, to our knowledge there are no reports about the use of tetracarbonyl Mo(0) complexes for the same purpose. This reason lead us to synthesize also a series of [Mo(CO)4(L)] complexes (L = 2,2’-bipyridyl and derivatives), testing them for electrochemical reduction of carbon dioxide. Our first results are quite promising, showing certain activity and selectivity in reducing CO2 to CO
Solid State NMR spectra and GIPAW plane-wave investigation of hydrogen storage materials
Full text linkCharacteristic redshift and intensity enhancement as far-IR fingerprints of the halogen bond involving aromatic donors
No full textSix halogen-bonded cocrystals involving aromatic donors have been studied by far-IR spectroscopy. Characteristic redshift and intensity enhancement of the C-I stretching band have been observed, which provided a distinct signature of the halogen bond involving iodopentafluorobenzene
SOLID-STATE NMR COUPLED WITH GIPAW AB-INITIO CALCULATIONS IN METAL HYDRIDES AND BOROHYDRIDES
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