Low-temperature binding of NO adsorbed on MIL-100(Al)-A case study for the application of high resolution pulsed EPR methods and DFT calculations

The low-temperature binding of nitric oxide (NO) in the metal-organic framework MIL-100(Al) has been investigated by pulsed electron nuclear double resonance and hyperfine sublevel correlation spectroscopy. Three NO adsorption species have been identified. Among them, one species has been verified experimentally to bind directly to an 27Al atom and all its relevant 14N and 27Al hyperfine interaction parameters have been determined spectroscopically. Those parameters fit well to the calculated ones of a theoretical cluster model, which was derived by density functional theory (DFT) in the present work and describes the low temperature binding of NO to the regular coordinatively unsaturated Al3+ site of the MIL-100(Al) structure. As a result, the Lewis acidity of that site has been characterized using the NO molecule as an electron paramagnetic resonance active probe. The DFT derived wave function analysis revealed a bent end-on coordination of the NO molecule adsorbed at that site which is almost purely ionic and has a weak binding energy. The calculated flat potential energy surface of this species indicates the ability of the NO molecule to freely rotate at intermediate temperatures while it is still binding to the Al3+ site. For the other two NO adsorption species, no structural models could be derived, but one of them is indicated to be adsorbed at the organic part of the metal-organic framework. Hyperfine interactions with protons, weakly coupled to the observed NO adsorption species, have also been measured by pulsed electron paramagnetic resonance and found to be consistent with their attribution to protons of the MIL-100(Al) benzenetricarboxylate ligand molecules

SmartRain – Aufbau eines Bürgermessnetzes zur Bestimmung und Analyse lokaler Niederschlagsverteilungen

Das Projekt SmartRain (https://smart-rain.de/) widmet sich dem Aufbau eines bürgerschaftlichen Messnetzes zur Bestimmung von Niederschlagsverteilungen in der Landeshauptstadt Dresden. Es wird dargelegt, welchen Wert eine smarte Datenerhebung im Bereich der Umweltsensorik haben kann, aber auch, mit welchen Herausforderungen bei der organisatorischen Umsetzung eines solchen Projektes gerechnet werden muss

Magnetic coupling of divalent metal centers in postsynthetic metal exchanged bimetallic DUT-49 MOFs by EPR spectroscopy

EPR measurements at X- (9.5 GHz), Q- (34 GHz) and W-band (94 GHz) on paddlewheel (PW) type post-synthetic metal exchanged DUT-49(M,M): M- Zn, Mn, Cu MOFs are here reported (DUT–Dresden University of Technology). Temperature-dependent X-band measurements are recorded from T = 7 K to T = 170 K on monometallic DUT-49(Cu), DUT-49(Mn), and bimetallic DUT-49(Cu0.7Zn0.3), DUT-49(Cu0.5Mn0.5) MOFs. In the case of the CuII - CuII dimers in DUT-49(Cu), an isotropic exchange coupling of the metal ions (2J = −240(11) cm−1) determined from the EPR intensity of the S = 1 spin state of the CuII–CuII dimers using the Bleaney Blowers equation. The sign of the found isotropic exchange coupling constant confirms an antiferromagnetic coupling between the cupric ions. Also, the MnII ions in the paddle wheels of DUT-49(Mn) are antiferromagnetically coupled. However, at low temperatures, EPR measurements reveal the presence of CuII and MnII monomers in DUT-49(Cu) and DUT-49(Mn), respectively, either associated with extra framework sites or defective paddle wheels. Otherwise, EPR signals observed for bimetallic DUT-49(Cu0.7Zn0.3) and DUT-49(Cu0.5Mn0.5) MOFs reveal the formation of mixed ion CuII–ZnII and CuII–MnII paddle wheels with SCuZn =1/2 and SCuMn = 2 spin states, respectively

Unveiling the atomistic and electronic structure of Ni II –NO adduct in a MOF-based catalyst by EPR spectroscopy and quantum chemical modelling †

The nature of the chemical bonding between NO and open-shell NiII ions docked in a metal–organic framework is fully characterized by EPR spectroscopy and computational methods. High-frequency EPR experiments reveal the presence of unsaturated NiII ions displaying five-fold coordination. Upon NO adsorption, in conjunction with advanced EPR methodologies and DFT/CASSCF modelling, the covalency of the metal–NO and metal–framework bonds is directly quantified. This enables unravelling the complex electronic structure of NiII–NO species and retrieving their microscopic structure

Electron Paramagnetic Resonance Characterization of Surface Sites in Metal-Organic Frameworks by Nitric Oxide Adsorption

TesisLima NorteEscuela de PosgradoAtención Integral del infante, niño y adolescenteEste trabajo de investigación partió del problema: ¿En qué medida el programa de modelado mejora la inteligencia emocional en los estudiantes de 5° de primaria del Colegio San Andrés, Lima-Cercado, 2015?, por lo que se planteó como objetivo general: Establecer en qué medida el programa de modelado mejora la inteligencia emocional en los estudiantes de 5° de primaria del Colegio San Andrés, Lima Cercado, 2015. El estudio utilizó el enfoque cuantitativo de tipo aplicada. El diseño fue cuasi experimental con pretest-postest y grupo control, se sometió a ambos grupos a un pretest y postest de inteligencia emocional, después de intervenir con el programa de modelado para mejorar la inteligencia emocional con el grupo experimental. La población estuvo compuesta por 66 estudiantes de ambos sexos que cursan el 5° de primaria durante el presente año, que tienen 10 años de edad. La muestra fue de 30 estudiantes seleccionados con el método no probabilístico de tipo intencional. La técnica de recolección de datos fue el cuestionario y el instrumento el inventario de Inteligencia Emocional BarOn ICE: NA adaptado y estandarizado para niños y adolescentes por Nelly Ugarriza Chávez y Liz Pajares del Águila.(2004) De acuerdo al análisis paramétrico con la prueba t, los resultados de la prueba de hipótesis evidenciaron que la media en el nivel de la inteligencia emocional de los estudiantes del grupo experimental fue (pretest 81.87, postest 91.13) y la media del grupo control fue (pretest 81, postest 83.27), evidenciándose una diferencia significativa de 7.86 puntos entre el grupo que desarrolló el experimento y el grupo que no fue puesto a experimentación. También se observa que el grupo experimental mejoró notablemente su coeficiente emocional en 9.26 puntos mientras que el grupo control ascendió 2.27 puntos. Además siendo p = .000 menor que α (p < α) y t = - 5.358 menor que -1.70 (punto crítico) se demuestra que los estudiantes del grupo experimental mejoraron su inteligencia emocional después de la aplicación del programa de modelado, respecto de los estudiantes del grupo control

Low-temperature binding of NO adsorbed on MIL-100(Al)-A case study for the application of high resolution pulsed EPR methods and DFT calculations

The low-temperature binding of nitric oxide (NO) in the metal-organic framework MIL-100(Al) has been investigated by pulsed electron nuclear double resonance and hyperfine sublevel correlation spectroscopy. Three NO adsorption species have been identified. Among them, one species has been verified experimentally to bind directly to an 27Al atom and all its relevant 14N and 27Al hyperfine interaction parameters have been determined spectroscopically. Those parameters fit well to the calculated ones of a theoretical cluster model, which was derived by density functional theory (DFT) in the present work and describes the low temperature binding of NO to the regular coordinatively unsaturated Al3+ site of the MIL-100(Al) structure. As a result, the Lewis acidity of that site has been characterized using the NO molecule as an electron paramagnetic resonance active probe. The DFT derived wave function analysis revealed a bent end-on coordination of the NO molecule adsorbed at that site which is almost purely ionic and has a weak binding energy. The calculated flat potential energy surface of this species indicates the ability of the NO molecule to freely rotate at intermediate temperatures while it is still binding to the Al3+ site. For the other two NO adsorption species, no structural models could be derived, but one of them is indicated to be adsorbed at the organic part of the metal-organic framework. Hyperfine interactions with protons, weakly coupled to the observed NO adsorption species, have also been measured by pulsed electron paramagnetic resonance and found to be consistent with their attribution to protons of the MIL-100(Al) benzenetricarboxylate ligand molecules

SmartRain – Aufbau eines Bürgermessnetzes zur Bestimmung und Analyse lokaler Niederschlagsverteilungen

Das Projekt SmartRain (https://smart-rain.de/) widmet sich dem Aufbau eines bürgerschaftlichen Messnetzes zur Bestimmung von Niederschlagsverteilungen in der Landeshauptstadt Dresden. Es wird dargelegt, welchen Wert eine smarte Datenerhebung im Bereich der Umweltsensorik haben kann, aber auch, mit welchen Herausforderungen bei der organisatorischen Umsetzung eines solchen Projektes gerechnet werden muss