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1.
Alexandru Vlasceanu Dr. Søren L. Broman Anne S. Hansen Anders B. Skov Prof. Dr. Martina Cacciarini Prof. Dr. Anders Kadziola Prof. Dr. Henrik G. Kjaergaard Prof. Dr. Kurt V. Mikkelsen Prof. Dr. Mogens Brøndsted Nielsen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10796-10800
The conversion and efficient storage of solar energy is recognized to hold significant potential with regard to future energy solutions. Molecular solar thermal batteries based on photochromic systems exemplify one possible technology able to harness and apply this potential. Herein is described the synthesis of a macrocycle based on a dimer of the dihydroazulene/vinylheptafulvene (DHA/VHF) photo/thermal couple. By taking advantage of conformational strain, this DHA–DHA macrocycle presents an improved ability to absorb and store incident light energy in chemical bonds (VHF–VHF). A stepwise energy release over two sequential ring‐closing reactions (VHF→DHA) combines the advantages of an initially fast discharge, hypothetically addressing immediate energy consumption needs, followed by a slow process for consistent, long‐term use. This exemplifies another step forward in the molecular engineering and design of functional organic materials towards solar thermal energy storage and release. 相似文献
2.
Suitably functionalized vinylheptafulvenes (VHFs) act as thermoswitches undergoing ring closure to the corresponding dihydroazulenes (DHAs). Here we present the synthesis of a new such thermoswitch incorporating two heptafulvene rings on a dicyanoethylene unit. The synthetic protocol explores both the tropylium species as an electrophile and as a leaving group in the generation of the heptafulvene units. The thermally induced ring closure was enhanced as a result of two accessible sites for the reaction to occur. 相似文献
3.
When dealing with nonlinear dynamical systems, it is important to have efficient, accurate and reliable tools for estimating both the linear and nonlinear system parameters from measured data. An approach for nonlinear system identification widely studied in recent years is “Reverse Path”. This method is based on broad-band excitation and treats the nonlinear terms as feedback forces acting on an underlying linear system. Parameter estimation is performed in the frequency domain using conventional multiple-input–multiple-output or multiple-input–single-output techniques. This paper presents a generalized approach to apply the method of “Reverse Path” on continuous mechanical systems with multiple nonlinearities. The method requires few spectral calculations and is therefore suitable for use in iterative processes to locate and estimate structural nonlinearities. The proposed method is demonstrated in both simulations and experiments on continuous nonlinear mechanical structures. The results show that the method is effective on both simulated as well as experimental data. 相似文献
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5.
E. Cattelain T. Thunberg T. Broman B. Romani C. di Pietro und E. Solarino 《Fresenius' Journal of Analytical Chemistry》1933,95(1-3):86-87
Ohne Zusammenfassung 相似文献
6.
Parker CR Tortzen CG Broman SL Schau-Magnussen M Kilså K Nielsen MB 《Chemical communications (Cambridge, England)》2011,47(21):6102-6104
Mild Lewis acids enhance the rate of the thermal conversion of vinylheptafulvene (VHF) to dihydroazulene (DHA). In the absence of light, stronger Lewis acids promote the otherwise photoinduced DHA to VHF conversion. 相似文献
7.
Angular distributions of transitions to 29 states in46Ti between 7.6 and 11.0 MeV excitation energy from the45Sc (3He,d) reaction at 15 MeV have been compared with DWBA predictions. The results support previously suggestedT=2 states in46Ti. 相似文献
8.
Anne U. Petersen Dr. Søren L. Broman Stine T. Olsen Anne S. Hansen Prof. Dr. Lin Du Prof. Dr. Anders Kadziola Prof. Dr. Thorsten Hansen Prof. Dr. Henrik G. Kjaergaard Prof. Dr. Kurt V. Mikkelsen Prof. Dr. Mogens Brøndsted Nielsen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):3968-3977
We present the synthesis and switching studies of systems with two photochromic dihydroazulene (DHA) units connected by a phenylene bridge at either para or meta positions, which correspond to a linear or cross‐conjugated pathway between the photochromes. According to UV/Vis absorption and NMR spectroscopic measurements, the meta‐phenylene‐bridged DHA–DHA exhibited sequential light‐induced ring openings of the two DHA units to their corresponding vinylheptafulvenes (VHFs). Initially, the VHF–DHA species was generated, and, ultimately, after continued irradiation, the VHF–VHF species. Studies in different solvents and quantum chemical calculations indicate that the excitation of DHA–VHF is no longer a local DHA excitation but a charge‐transfer transition that involves the neighboring VHF unit. For the linearly conjugated para‐phenylene‐bridged dimer, electronic communication between the two units is so efficient that the photoactivity is reduced for both the DHA–DHA and DHA–VHF species, and DHA–DHA, DHA–VHF, and VHF–VHF were all present during irradiation. In all, by changing the bridging unit, we can control the degree of stepwise photoswitching. 相似文献
9.
Aromaticity‐Controlled Energy Storage Capacity of the Dihydroazulene‐Vinylheptafulvene Photochromic System
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Anders B. Skov Dr. Søren Lindbæk Broman Anders S. Gertsen Dr. Jonas Elm Dr. Martyn Jevric Prof. Dr. Martina Cacciarini Prof. Dr. Anders Kadziola Prof. Dr. Kurt V. Mikkelsen Prof. Dr. Mogens Brøndsted Nielsen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14567-14575
Photochemical conversion of molecules into high‐energy isomers that, after a stimulus, return to the original isomer presents a closed‐cycle of light‐harvesting, energy storage, and release. One challenge is to achieve a sufficiently high energy storage capacity. Here, we present efforts to tune the dihydroazulene/vinylheptafulvene (DHA/VHF) couple through loss/gain of aromaticity. Two derivatives were prepared, one with aromatic stabilization of DHA and the second of VHF. The consequences for the switching properties were elucidated. For the first type, sigmatropic rearrangements of DHA occurred upon irradiation. Formation of a VHF complex could be induced by a Lewis acid, but addition of H2O resulted in immediate regeneration of DHA. For the second type, the VHF was too stable to convert into DHA. Calculations support the results and provide new targets. We predict that by removing one of the two CN groups at C‐1 of the aromatic DHA, the heat storage capacity will be further increased, as will the life‐time of the VHF. Calculations also reveal that a CN group at the fulvene ring retards the back‐reaction, and we show synthetically that it can be introduced regioselectively. 相似文献
10.
Bag-SPE is a solid-phase extraction (SPE) technique here applied to sample pharmaceutical residues in wastewater. The device,
consisting of 20 mg polystyrene-divinylbenzene (PS-DVB) enclosed in a woven polyester fabric was immersed into a 20-mL sample.
Extraction of the analytes was performed under gentle rotation (25 rpm) until distribution equilibrium was achieved (4 h).
The extraction efficiency for thirteen pharmaceuticals was evaluated for the bag-SPE sampler compared to a conventional SPE
cartridge (Oasis HLB). All analyses were determined on an ultra-performance liquid chromatography (UPLC) coupled to a quadrupole
time-of-flight (QToF) mass spectrometer. The detection limit of the bag-SPE technique for the analytes in wastewater ranged
from 15–100 ng/L with recoveries between 20.7% and 58.2% and ion suppressions between 2.2% and 53.2%. Although the extraction
efficiencies were lower with the bag-SPE sampler compared to the SPE technique, the two methods showed similar detection limits
due to the lower ion suppression experienced with the bag-SPE. The results demonstrate that bag-SPE is an attractive alternative
to the more, in terms of manual handling, demanding SPE technique. 相似文献