TY - JOUR A1 - Otter, Dirk A1 - Mondal, Suvendu Sekhar A1 - Alrefai, Anas A1 - Krätz, Lorenz A1 - Holdt, Hans-Jürgen A1 - Bart, Hans-Jörg T1 - Characterization of an isostructural MOF series of Imidazolate Frameworks Potsdam by means of sorption experiments with water vapor JF - Nanomaterials N2 - Sorption measurements of water vapor on an isoreticular series of Imidazolate Frameworks Potsdam (IFP), based on penta-coordinated metal centers with secondary building units (SBUs) connected by multidentate amido-imidate-imidazolate linkers, have been carried out at 303.15 K. The isotherm shapes were analyzed in order to gain insight into material properties and compared to sorption experiments with nitrogen at 77.4 K and carbon dioxide at 273.15 K. Results show that water vapor sorption measurements are strongly influenced by the pore size distribution while having a distinct hysteresis loop between the adsorption and desorption branch in common. Thus, IFP-4 and -8, which solely contain micropores, exhibit H4 (type I) isotherm shapes, while those of IFP-1, -2 and -5, which also contain mesopores, are of H3 (type IV) shape with three inflection points. The choice of the used linker substituents and transition metals employed in the framework has a tremendous effect on the material properties and functionality. The water uptake capacities of the examined IFPs are ranging 0.48 mmol g(-1) (IFP-4) to 6.99 mmol g(-1) (IFP-5) and comparable to those documented for ZIFs. The water vapor stability of IFPs is high, with the exception of IFP-8. KW - material characterization KW - water vapor KW - adsorption KW - hysteresis KW - Imidazolate Frameworks Potsdam Y1 - 2021 U6 - https://doi.org/10.3390/nano11061400 SN - 2079-4991 VL - 11 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Schwarze, Thomas A1 - Sperlich, Eric A1 - Müller, Thomas A1 - Kelling, Alexandra A1 - Holdt, Hans-Jürgen T1 - Synthesis efforts of acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis(dialkylamino)maleonitriles as fluorescent probes for cations and a new colorimetric copper(II) chemodosimeter JF - Helvetica chimica acta N2 - In this article, we report on the synthesis of acyclic bis(monoalkylamino)maleonitriles and on the intended synthesis of macrocyclic bis(dialkylamino)maleonitriles to get fluorescent probes for cations. During our efforts to synthesize macrocyclic bis(dialkylamino)maleonitriles, we were only able to isolate macrocyclic bis(dialkylamino)-fumaronitriles. The synthesis of macrocyclic bis(dialkylamino)maleonitriles is challenging, due to the fact that bis-(dialkylamino)fumaronitriles are thermodynamically more stable than the corresponding bis(dialkylamino)-maleonitriles. Further, it turned out that the acyclic bis(monoalkylamino)maleonitriles and macrocyclic bis-(dialkylamino)fumaronitriles are no suitable tools to detect cations by a strong fluorescence enhancement. Further, only the bis(monoalkylamino)maleonitriles, which are bearing a 2-pyridyl unit as an additional complexing unit, are able to selectively recognize copper(II) by a color change from yellow to red. KW - copper KW - fumaronitrile KW - ligands KW - macrocycles KW - maleonitrile Y1 - 2021 U6 - https://doi.org/10.1002/hlca.202100028 SN - 1522-2675 VL - 104 IS - 6 SP - e2100028 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schwarze, Thomas A1 - Kelling, Alexandra A1 - Sperlich, Eric A1 - Holdt, Hans-Jürgen T1 - Influence of regioisomerism in 9-anthracenyl-substituted dithiodicyanoethene derivatives on photoinduced electron transfer controlled by intramolecular charge transfer JF - ChemPhotoChem N2 - In this paper, we report on the fluorescence behaviour of three regioisomers which consist of two 9-anthracenyl fluorophores and of differently substituted dithiodicyanoethene moieties. These isomeric fluorescent probes show different quantum yields (phi(f)). In these probes, an oxidative photoinduced electron transfer (PET) from the excited 9-anthracenyl fluorophore to the dithiodicyanoethene unit quenches the fluorescence. This quenching process is accelerated by an intramolecular charge transfer (ICT) of the push-pull pi-electron system of the dithiodicyanoethene group. The acceleration of the PET depends on the strength of the ICT unit. The higher the dipole moment of the ICT unit, the stronger the observed fluorescence quenching. To the best of our knowledge, this is the first report of a regioisomeric influence on an oxidative PET by an ICT. KW - anthracene KW - charge transfer KW - electron transfer KW - fluorescence KW - isomerism Y1 - 2021 U6 - https://doi.org/10.1002/cptc.202100070 SN - 2367-0932 VL - 5 IS - 10 SP - 911 EP - 914 PB - Wiley-VCH CY - Weinheim ER -