Structural and magnetic properties of Mn 12 -Stearate nanomagnets

Efficient Homogeneous Electrocatalytic Water Oxidation by a Manganese Cluster with an Overpotential of Only 74 mV

“…[14] Theh igh similarity between the two spectra, specifically in the region of the carboxylate bands (u = 2000-1000 cm À1 ), suggests that Mn 12 TH retains the [Mn 12 O 12 (O 2 CR) 16 (H 2 O) 4 ]s tructure (see Figure S2). This structure was further supported by powder XRD analysis showing diffraction peaks at 2q values of 7.17, 8.96, 10.06, and 13.66, consistent with the reported powder XRD pattern of Mn 12 stearate [16] and of pure crystals of Mn 12 Ac synthesized in our lab ( Figure 1b). Additionally,t he ESI-MS analysis of Mn 12 TH in water showed apeak at 3627.1 (cal.…”

“…[9] Further advances require the development of catalysts that are not only based on earthabundant metals,b ut are also stable,f ast and, most importantly,c an perform with as low overpotential as possible to meet practical applications.O ne approach to address these goals is to mimic the structure and function of the oxygenevolving complex (OEC) in photosystem II (PSII), which is am anganese-oxo cluster.A lthough various structural mimics of the OEC are reported, [10] manganese-based homogeneous water oxidation electrocatalysts are very scant. [11] Recently,o ur group reported the water-soluble manganesebased electrocatalyst [Mn 12 O 12 (O 2 CC 6 H 3 (OH) 2 ) 16 (H 2 O) 4 ] (Mn 12 DH), [12] which structurally mimics the OEC and operates at pH 6with alow overpotential of only 334 mV,average k obs of 0.035 s À1 (based on Foot-of-the-wave analysis,FOWA), and Faradic efficiency( FE) of 80 %( see Table T1 in the Supporting Information). We suggested that the hydroxy groups on the organic ligands,w hich can be described as the second coordination sphere of the manganese catalyst, may contribute to the catalysis by either proton transfer or shuttling and/or by facilitating the formation of high-valence species required for water oxidation.…”

“…Thehighly water-soluble Mn 12 TH cluster was prepared in aqueous medium by adopting,w ith some modifications,t he synthetic procedure used for the synthesis of [Mn 12 O 12 -(O 2 CCH 3 ) 16 (H 2 O) 4 ]( Mn 12 Ac) [14] .T he full synthesis is described in the Supporting Information. Mn 12 TH was characterized by acollection of different analytical methods.The IR spectrum showed some distinct peaks in the range of u = 610-720 cm À1 corresponding to the various Mn À Os tretching modes and at u = 1023, 1041 cm À1 for the Ar-O-H stretching frequencies.…”

“…Mn 12 TH was characterized by acollection of different analytical methods.The IR spectrum showed some distinct peaks in the range of u = 610-720 cm À1 corresponding to the various Mn À Os tretching modes and at u = 1023, 1041 cm À1 for the Ar-O-H stretching frequencies. [15] This spectrum was further compared to the IR spectrum of [Mn 12 O 12 (O 2 CC 6 H 5 ) 16 (H 2 O) 4 ]( Mn 12 Bz), which we synthesized according to aliterature method. [14] Theh igh similarity between the two spectra, specifically in the region of the carboxylate bands (u = 2000-1000 cm À1 ), suggests that Mn 12 TH retains the [Mn 12 O 12 (O 2 CR) 16 (H 2 O) 4 ]s tructure (see Figure S2).…”

“…[15] This spectrum was further compared to the IR spectrum of [Mn 12 O 12 (O 2 CC 6 H 5 ) 16 (H 2 O) 4 ]( Mn 12 Bz), which we synthesized according to aliterature method. [14] Theh igh similarity between the two spectra, specifically in the region of the carboxylate bands (u = 2000-1000 cm À1 ), suggests that Mn 12 TH retains the [Mn 12 O 12 (O 2 CR) 16 (H 2 O) 4 ]s tructure (see Figure S2). This structure was further supported by powder XRD analysis showing diffraction peaks at 2q values of 7.17, 8.96, 10.06, and 13.66, consistent with the reported powder XRD pattern of Mn 12 stearate [16] and of pure crystals of Mn 12 Ac synthesized in our lab ( Figure 1b).…”