A hydrogen‐bonding donor–acceptor system, Co2Fe2(bpy*)4(CN)6(tp*)2(PF6)2⋅2ABA⋅4BN⋅2PE (1 solv), was prepared by co‐crystallization of an external stimuli‐responsive cyanide‐bridged tetranuclear ...Co2Fe2 complex and bifunctional hydrogen‐bonding donors, p‐aminobenzoic acid. Compound 1 solv exhibited a gradual electron‐transfer‐coupled spin transition (ETCST), and the removal of solvent molecules led to an abrupt thermal ETCST behavior with increased transition temperature. X‐ray structural analysis revealed that the modification of ETCST was caused by a significant alteration of a hydrogen‐bonding mode between the tetranuclear Co2Fe22+ cations and ABA molecules. Variable temperature IR measurements indicated that the desolvated form, 1 desolv, showed dynamic alteration of hydrogen‐bonding interactions coupled with thermal ETCST behavior. These results suggested that the tetranuclear Co2Fe2 complex shows solid‐state modulations of hydrogen‐bond strengths by external stimuli.
Mixed‐valent compounds: A hydrogen‐bonding donor–acceptor system composed of external stimuli‐responsive Co2Fe22+ cations showed solid‐state alterations of hydrogen‐bonding interactions induced by solvent release and thermal intramolecular electron transfers (see scheme).
A mononuclear FeII complex, prepared with a Brønsted diacid ligand, H2L (H2L=2‐5‐phenyl‐1H‐pyrazole‐3‐yl 6‐benzimidazole pyridine), shows switchable physical properties and was isolated in five ...different electronic states. The spin crossover (SCO) complex, FeII(H2L)2(BF4)2 (1A), exhibits abrupt spin transition at T1/2=258 K, and treatment with base yields a deprotonated analogue FeII(HL)2 (1B), which shows gradual SCO above 350 K. A range of FeIII analogues were also characterized. FeIII(HL)(H2L)(BF4)Cl (1C) has an S=5/2 spin state, while the deprotonated complexes FeIII(L)(HL), (1D), and (TEA)FeIII(L)2, (1E) exist in the low‐spin S=1/2 state. The electronic properties of the five complexes were fully characterized and we demonstrate in situ switching between multiple states in both solution and the solid‐state. The versatility of this simple mononuclear system illustrates how proton donor/acceptor ligands can vastly increase the range of accessible states in switchable molecular devices.
Switch that: A mononuclear FeII complex prepared with an asymmetric Brønsted ligand exhibited multi‐state switchable properties and was isolated in five distinct electronic states. By modifying the degree of protonation, both spin‐ and redox‐interconversion was observed, resulting in a range of tunable magnetic, electrochemical, and optical properties. SCO=spin crossover.
Abstract
Six new mononuclear Fe
III
(L
Br,Cl
)X‐complexes (L
Br,Cl
is the dianionic penta‐N
3
O
2
‐dentate Schiff base ligand N,N′‐bis(2’‐hydroxy‐3‐bromo‐5‐chlorobenzylidene)‐1,6‐diamino‐3‐azahexane; ...X: Cl
−
, N
3
−
, NCO
−
, NCS
−
, NCSe
−
, CN
−
) were synthesized and their structures, magnetic and electrochemical properties studied. Structure analysis and magnetic measurements showed that Fe
III
(L
Br,Cl
)CN is in the low spin state and the other five complexes are in high spin states. Furthermore, the trinuclear mixed valent cobalt complex {Co
III
(L
H,H
)CN
2
Co
II
(1‐methylimidazole)
3
(H
2
O)} was prepared and its magnetic behavior studied.
An Arduino based Mössbauer spectrometer Jahns, Moritz; Klimke, Stephen; Natke, Dominik ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2019, Letnik:
940
Journal Article
Recenzirano
A key part of Mössbauer (MB) spectroscopy is the selection of the resonant energy range out of a detected γ-ray spectrum. As the detection of the entire γ-ray source spectrum generates high count ...rates, selection of the photons having the MB transition energy requires fast processing. To achieve this goal with the MIMOS II instrument, developed and built by the group of Göstar Klingelhöfer at the TU Darmstadt and JOGU Mainz, multiple sets of two comparator units, using fast operational amplifiers to define a certain energy window, are implemented in the instrument’s main electronics board. These analogue circuits use stabilized reference voltages to set the thresholds. Today’s fast microcontroller based analogue-to-digital converters (ADC), such as the Arduino Due, show better signal to noise ratio and possibilities for a two-dimensional extension of Mössbauer spectroscopy.
Nanoparticle‐based voluminous 3D networks with low densities are a unique class of materials and are commonly known as aerogels. Due to the high surface‐to‐volume ratio, aerogels and xerogels might ...be suitable materials for applications in different fields, e.g. photocatalysis, catalysis, or sensing. One major difficulty in the handling of nanoparticle‐based aerogels and xerogels is the defined patterning of these structures on different substrates and surfaces. The automated manufacturing of nanoparticle‐based aerogel‐ or xerogel‐coated electrodes can easily be realized via inkjet printing. The main focus of this work is the implementation of the standard nanoparticle‐based gelation process in a commercial inkjet printing system. By simultaneously printing semiconductor nanoparticles and a destabilization agent, a 3D network on a conducting and transparent surface is obtained. First spectro‐electrochemical measurements are recorded to investigate the charge–carrier mobility within these 3D semiconductor‐based xerogel networks.
Semiconductor nanoparticle‐based aerogel‐coated electrodes are manufactured automatically via inkjet printing. By simultaneously printing a destabilization agent and semiconductor nanoparticles, a 3D aerogel‐type network on a conducting and transparent surface is obtained. Furthermore, the charge‐carrier mobility within the 3D aerogel‐type network is investigated via spectro‐electrochemical measurements.
Molecules exhibiting solid‐state alterations of pKa by external stimuli are expected to be a useful switching unit in multifunctional molecular solids. It was shown that solid‐state alterations of ...hydrogen‐bonding interactions induced by solvent release and thermal intramolecular electron transfers in a hydrogen‐bonding donor–acceptor system composed of external stimuli‐responsive Co2Fe22+ cations. More information can be found in the Communication by M. Nihei, H. Oshio, et al. on page 7449.
Six new mononuclear FeIII(LBr,Cl)X‐complexes (LBr,Cl is the dianionic penta‐N3O2‐dentate Schiff base ligand N,N′‐bis(2’‐hydroxy‐3‐bromo‐5‐chlorobenzylidene)‐1,6‐diamino‐3‐azahexane; X: Cl−, N3−, ...NCO−, NCS−, NCSe−, CN−) were synthesized and their structures, magnetic and electrochemical properties studied. Structure analysis and magnetic measurements showed that FeIII(LBr,Cl)CN is in the low spin state and the other five complexes are in high spin states. Furthermore, the trinuclear mixed valent cobalt complex {CoIII(LH,H)CN2CoII(1‐methylimidazole)3(H2O)} was prepared and its magnetic behavior studied.
A new series of FeIII Schiff base complexes and a new mixed valence CoIII2CoII Prussian blue analogue with a similar ligand are presented. Crystal structure, magnetic data, and redox properties were measured and put into context with other metal to metal charge transfer complexes.
In article number 1902186, Nadja C. Bigall and co‐workers manufacture semiconductor nanoparticle‐based aerogel‐coated electrodes automatically via inkjet printing. By simultaneously printing a ...destabilization agent and semiconductor nanoparticles, a 3D aerogel‐type network on a conducting and transparent surface is obtained. Furthermore, the charge‐carrier mobility within the 3D aerogel‐type network is investigated via spectro‐electrochemical measurements.
A mononuclear FeII complex, prepared with a Brønsted diacid ligand, H2L (H2L=2‐5‐phenyl‐1H‐pyrazole‐3‐yl 6‐benzimidazole pyridine), shows switchable physical properties and was isolated in five ...different electronic states. The spin crossover (SCO) complex, FeII(H2L)2(BF4)2 (1A), exhibits abrupt spin transition at T1/2=258 K, and treatment with base yields a deprotonated analogue FeII(HL)2 (1B), which shows gradual SCO above 350 K. A range of FeIII analogues were also characterized. FeIII(HL)(H2L)(BF4)Cl (1C) has an S=5/2 spin state, while the deprotonated complexes FeIII(L)(HL), (1D), and (TEA)FeIII(L)2, (1E) exist in the low‐spin S=1/2 state. The electronic properties of the five complexes were fully characterized and we demonstrate in situ switching between multiple states in both solution and the solid‐state. The versatility of this simple mononuclear system illustrates how proton donor/acceptor ligands can vastly increase the range of accessible states in switchable molecular devices.
Molekularer Mehrfachschalter: Ein einkerniger FeII‐Komplex mit asymmetrischem Brønsted‐Liganden zeigt mehrstufige schaltbare Eigenschaften und wurde in fünf verschiedenen elektronischen Zuständen isoliert. Durch Modifikation des Protonierungsgrades kann sowohl Spin‐ als auch Redox‐Interkonversion erreicht werden, resultierend in einer Reihe abstimmbarer magnetischer, elektrochemischer und optischer Eigenschaften. SCO=Spin‐Crossover.
PDF
