The effect of ligands with heavy donor atoms on the magnetic anisotropy of the pseudo-tetrahedral cobalt complexes, Co(quinoline)2I2 (1) and Co(EPh3)2I2 (2-3) (E = P, As) has been investigated. The ...axial zero-field splitting parameter D was found to vary from +9.2 cm(-1) in 1 to -36.9 cm(-1) in 2 and -74.7 cm(-1) in 3. Compounds 2 and 3 exhibit slow relaxation of the magnetization up to 4 K under an applied dc field, indicating SMM behavior.
Given the recent advent of mononuclear single‐molecule magnets (SMMs), a rational approach based on lanthanides with axially elongated f‐electron charge cloud (prolate) has only recently received ...attention. We report herein a new SMM, Li(THF)4Er{N(SiMe3)2}3Cl⋅2 THF, which exhibits slow relaxation of the magnetization under zero dc field with an effective barrier to the reversal of magnetization (ΔEeff/kB=63.3 K) and magnetic hysteresis up to 3 K at a magnetic field sweep rate of 34.6 Oe s−1. This work questions the theory that oblate or prolate lanthanides must be stabilized with the appropriate ligand framework in order for SMM behavior to be favored.
Riding the wave of erbium SMMs: The first trigonal pyramidal mononuclear erbium(III) single‐molecule magnet (SMM) was synthesized and its magnetic properties investigated. Despite containing an axial Cl− ligand, which is expected to reduce the prolate nature of the erbium(III) ion, the molecule exhibits out‐of‐phase signals in the ac susceptibility data in the absence of an external field and hysteresis behavior up to 3 K.
The geometry of cobalt(
ii
) ions in the axially distorted octahedral cation in Co(MeCN)
6
(BF
4
)
2
(
1
) was compared to the trigonal prismatic cation in CoTp
py
PF
6
(
2
) which revealed ...significant differences in magnetic anisotropy. Combined experimental and
ab initio
CASSCF/NEVPT2 calculations support the observed zero field SMM behaviour for
2
, with easy axis anisotropy, attributed to the rigidity of the trigonal prismatic ligand. Strong transverse anisotropy for
1
leads to significant quantum tunnelling processes.
Combined experimental and
ab initio
calculations attribute the suppression of quantum tunneling and zero-field SMM behavior in the trigonal prismatic CoTp
py
PF
6
(
2
), evidenced by hysteresis up to 3 K, to the enforced rigidity and axial geometry.
In this work, heterostructures of coupled TiO2@MoS2 with different phases of MoS2 were synthesized via hydrothermal technique. The prepared materials were characterized using various techniques, ...including XRD, SEM, TEM, BET, and UV-vis. The optimized nanocoposites were tested for photocatalytic degradation of Methyl Orange (MO) under visible light radiation and adsorption of Rhodmin b (RhB) and Methelene Blue (MB). The TiO2@1T/2H-MoS2 heterostructures exhibit a narrow bandgap compared to the other materials. A remarkable photodegradation efficiency of TiO2@1T/2H-MoS2 was observed, which completely degraded 20 ppm of MO after 60 min. This can be assigned to the formation of unique heterostructures with aligned energy bands between MoS2 nanosheets and TiO2 nanobelts. The formation of these novel interfaces promoted the electron transfer and increased the separation efficiency of carriers, resulting in high photocatalytic degradation. Furthermore, the adsorption efficiency of TiO2@1T/2H-MoS2 was unique, 20 ppm solutions of RhB and MB were degraded after only 1 and 2 min respectively. The superior adsorption performance of the TiO2@1T/2H-MoS2 can be attributed to its high surface area (279.9 m2/g) and the rich concentration of active sites. This study provides a powerful way for designing an effective photocatalyst and adsorbent TiO2 based nanocomposites for water remediation.
To ensure maximum comfort for the wearer, electronic components that include energy harvesters need to be mechanically conformable. In this context, we demonstrate a versatile, cost-effective and ...efficient method for fabricating graphene supercapacitor electrodes using Laser Induced Graphene (LIG). A CO 2 laser beam instantly transforms the irradiated polyethersulfone polymer (PES) into a highly porous carbon structure. The LIG method was used to deposit graphene layers on graphite sheets to produce the supercapacitor electrodes. Graphene formation and morphology were examined and confirmed using several techniques including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) spectroscopy, Raman Spectroscopy and Fourier transform infrared spectroscopy (FTIR). Moreover, the electrochemical characterization was performed in different electrolytes (NaOH and KOH). At 5 mV s −1 , the LIG electrode achieved 165 mF cm −2 and 250 mF cm −2 in NaOH and KOH electrolytes, respectively. Consequently, we show that a wearable symmetric supercapacitor device with LIG electrodes achieved 98.5 mF cm −2 at 5 mV s −1 in KOH electrolyte. The device demonstrated an energy density of <inline-formula> <tex-math notation="LaTeX">11.3~\mu </tex-math></inline-formula>Wh.cm −2 with power density of 0.33 mWcm −2 at 0.5 mA cm −2 . The retention of capacitance was 75% after 2000 cycles, with outstanding performance for the comparable graphene-based electrodes. These results further validate the use of LIG for developing flexible energy harvesters for wearable applications.
The air-stable mononuclear Co(ii) compounds Co
(Tpm)
ClO
(
, Tpm = tris(pyrazol-1-yl)methane), Co
(Tpm)
BPh
·2MeCN (
) with trigonal antiprismatic geometry (trigonally elongated octahedral ...geometry) are reported. Magnetic and theoretical studies reveal that the complexes exhibit single-molecule magnet behavior with uniaxial anisotropy and a huge energy difference between ground and first excited Karmers' doublets (∼200 cm
). Under applied DC fields, compounds
and
exhibit frequency and temperature dependence of the imaginary susceptibility. The fit of the data to an Orbach relaxation process yields effective energy barriers of 30.6(1) and 44.7(6) cm
for
and
, respectively, but there is no real state at that energy. The inclusion of tunneling, direct and Raman relaxation processes leads to the conclusion that the inclusion of an Orbach process is not required to provide a good fit to the data. More interestingly, a detailed study of the dependence of the relaxation time with field shows that for these Kramers' ions, tunneling is the predominant process at low temperature and that differences in the counteranion allow for a tuning of the Raman process at higher temperatures. These findings underscore the fact that large uniaxial anisotropy can be achieved in hexacoordinate Co(ii) trigonal antiprismatic complexes which is an unexplored geometry in mononuclear single molecule magnets.
MoS2 is a very attractive material and has been well studied for potential applications in various areas. However, due to the wide variety of factors affecting the molecular and electronic structure ...of MoS2, several contradictory reports about the adsorptive and photocatalytic properties of such materials have been published. In most of these reports, the effect of the actual phase of the materials on the properties was neglected. Here, different phases of MoS2 nanosheets (1T/2H, 1T/3R and 2H) have been obtained using the hydrothermal method with different Mo : S molar ratios and different autoclave filling ratios. The obtained materials have been thoroughly characterized using Raman, UV-vis, powder XRD, SEM, TEM and XPS measurements in order to accurately identify the existing phases in each material. A comparative study of the photocatalytic organic dye degradation efficiency under white light irradiation has been conducted using methyl orange to correlate the different activity of each material to the respective phase composition. The results indicate a much higher performance of the 1T/2H phase compared to the 2H and 3R phases. Detailed computational studies of the different phases revealed the emergence of mid-gap states upon introducing 1T sites into the 2H lattice. This leads to the improvement of the photocatalytic activity of 1T/2H compared to the other prepared materials.
Searching for a connection between the two‐electron redox behavior of Group‐14 elements and their possible use as platforms for the photoreductive elimination of chlorine, we have studied the ...photochemistry of (o‐(Ph2P)C6H4)2GeIVCl2PtIICl2 and (o‐(Ph2P)C6H4)2ClGeIIIPtIIICl3, two newly isolated isomeric complexes. These studies show that, in the presence of a chlorine trap, both isomers convert cleanly into the platinum germyl complex (o‐(Ph2P)C6H4)2ClGeIIIPtICl with quantum yields of 1.7 % and 3.2 % for the GeIV–PtII and GeIII–PtIII isomers, respectively. Conversion of the GeIV–PtII isomer into the platinum germyl complex is a rare example of a light‐induced transition‐metal/main‐group‐element bond‐forming process. Finally, transient‐absorption‐spectroscopy studies carried out on the GeIII–PtIII isomer point to a ligand arene–Cl. charge‐transfer complex as an intermediate.
A novel platinum dichloride complex supported by an ambiphilic bisphosphinodichlorogermane ligand photo‐isomerizes into a tetravalent platinum trichloride germyl complex. Further irradiation of this new complex triggers the elimination of chlorine and the formation of a covalent Pt–Ge bond. Transient absorption spectroscopy points to the intermediacy of a charge‐transfer complex involving the nascent chlorine atom and the aromatic ligand.
A series of trans-dicyanide vanadium(III) compounds based on acetylacetonate, (PPN)VIII(acac)2(CN)2·(PPN)Cl·2MeCN (1), and salen ligands, (Et4N)VIII(salen)(CN)2 (2a), ...(PPN)VIII(MeOsalen)(CN)2·DMF·2MeCN (3), and (PPN)VIII(salphen)(CN)2·DMF (4) salen = N,N′-ethylenebis(salicyl-imine), MeOsalen = N,N′-ethylenebis(methoxysalicylimine), salphen = N,N′-phenylenebis(salicyl-imine), and PPN = bis(triphenylphosphine)iminium, were prepared and structurally characterized. High-field EPR studies reveal that the complexes exhibit moderate magnetic anisotropy with positive D values of +5.70, +3.80, +4.05, and +3.99 cm–1 for 1–4, respectively.
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