0000000000826678
AUTHOR
Hendrik V. Schröder
Strong Emission Enhancement in pH-Responsive 2:2 Cucurbit[8]uril Complexes
Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional con…
Evaluation of multivalency as an organization principle for the efficient synthesis of doubly and triply threaded amide rotaxanes
Mono-, di- and trivalent pseudorotaxanes with tetralactam macrocycle hosts and axles containing diamide binding stations as the guests have been synthesised. Their threading behaviour was analyzed in detail by NMR experiments and isothermal titration calorimetry. An X-ray crystal structure of the monovalent pseudorotaxane confirms the binding motif. Double mutant cycle analysis provides the effective molarities and insight into the chelate cooperativity of multivalent binding. While the second binding event in a trivalent pseudorotaxane exhibits a slightly positive cooperativity, the third binding is nearly non-cooperative. Nevertheless, the enhanced binding affinities resulting from the mu…
An aryl-fused redox-active tetrathiafulvalene with enhanced mixed-valence and radical-cation dimer stabilities.
Molecular recognition of stable organic radicals is a relatively novel, but important structural binding motif in supramolecular chemistry. Here, we report on a redox-switchable veratrole-fused tetrathiafulvalene derivative VTTF which is ideally suited for this purpose and for the incorporation into stimuli-responsive systems. As revealed by electrochemistry, UV/Vis measurements, X-ray analysis, and electrocrystallisation, VTTF can be reversibly oxidised to the corresponding radical-cation or dication which shows optoelectronic and structural propterties similar to tetrathiafulvalene and tetrakis(methylthio)tetrathiafulvalene. However, theoretical calculations, variable temperature EPR, and…
Heads or Tails? Sandwich-Type Metallocomplexes of Hexakis(2,3-di-O-methyl)-α-cyclodextrin
Native and synthetically modified cyclodextrins (CDs) are useful building blocks in construction of large coordination complexes and porous materials with various applications. Sandwich-type complexes (STCs) are one of the important groups in this area. Usually, coordination of secondary hydroxyls or the “head” portal of native CD molecules to a notional multinuclear ring of metal cations leads to formation of head-to-head STCs. Our study introduces a new CD-ligand, hexakis(2,3-di-O-methyl)-α-cyclodextrin, which enables formation of intriguing head-to-head, but also novel tail-to-tail STCs. Homometallic silver-based head-to-head STCs, AgPF6-STC and AgClO4-STC, were obtained by coordination …
Redox-Responsive Host-Guest Chemistry of a Flexible Cage with Naphthalene Walls
“Naphthocage”, a naphthalene-based organic cage, reveals very strong binding (up to 1010 M–1) to aromatic (di)cationic guests, i.e., the tetrathiafulvalene mono- and dication and methyl viologen. Intercalation of the guests between two naphthalene walls is mediated by C–H···O, C–H···π, and cation···π interactions. The guests can be switched into and out of the cage by redox processes with high binding selectivity. Oxidation of the flexible cage itself in the absence of a guest leads to a stable radical cation with the oxidized naphthalene intercalated between and stabilized by the other two. Encapsulated guest cations are released from the cavity upon cage oxidation, paving the way to futur…
Redox-Responsive Host–Guest Chemistry of a Flexible Cage with Naphthalene Walls
"Naphthocage", a naphthalene-based organic cage, reveals very strong binding (up to 1010 M-1) to aromatic (di)cationic guests, i.e., the tetrathiafulvalene mono- and dication and methyl viologen. Intercalation of the guests between two naphthalene walls is mediated by C-H···O, C-H···π, and cation···π interactions. The guests can be switched into and out of the cage by redox processes with high binding selectivity. Oxidation of the flexible cage itself in the absence of a guest leads to a stable radical cation with the oxidized naphthalene intercalated between and stabilized by the other two. Encapsulated guest cations are released from the cavity upon cage oxidation, paving the way to futur…
Dual-stimuli pseudorotaxane switches under kinetic control
A series of dumbbell-shaped sec-ammonium salts with bulky (pseudo)stoppers (‘speed bumps’) were tested for their ability to form pseudorotaxanes with a redox-switchable, tetrathiafulvalene (TTF)-decorated [24]crown-8 ether. Depending on the size of the pseudostoppers, fast (less than ten minutes), slow (hours to days) and very slow (no pseudorotaxanes observed) threading has been observed. NMR spectroscopy as well as tandem mass spectrometry indicate the formation of non-threaded face-to-face complexes prior to pseudorotaxanes formation. Both isomers can be distinguished by their substantially different stability in collision-induced dissociation (CID) experiments. Two external stimuli affe…
Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes
Crown ethers are common building blocks in supramolecular chemistry and are frequently applied as cation sensors or as subunits in synthetic molecular machines. Developing switchable and specifically designed crown ethers enables the implementation of function into molecular assemblies. Seven tailor-made redox-active crown ethers incorporating tetrathiafulvalene (TTF) or naphthalene diimide (NDI) as redox-switchable building blocks are described with regard to their potential to form redox-switchable rotaxanes. A combination of isothermal titration calorimetry and voltammetric techniques reveals correlations between the binding energies and redox-switching properties of the corresponding ps…
Heads or Tails? Sandwich-Type Metallo Complexes of Hexakis(2,3-di-O-methyl)-α-cyclodextrin
Native and synthetically modified cyclodextrins (CDs) are useful building blocks in the construction of large coordination complexes and porous materials with various applications. Sandwich-type co...
Chiroptical inversion of a planar chiral redox-switchable rotaxane.
Reversible redox-switching of a planar chiral [2]rotaxane with a tetrathiafulvalene-bearing crown ether macrocycle generates a complete sign reversal of the main band in the ECD spectrum, as shown by experiment and rationalised by DFT calculations.
Strong Emission Enhancement in pH‐Responsive 2:2 Cucurbit[8]uril Complexes
Organic fluorophores, particularly stimuli-responsive molecules, are very interesting for biological and material sciences applications, but frequently limited by aggregation- and rotation-caused photoluminescence quenching. A series of easily accessible bipyridinium fluorophores, whose emission is quenched by a twisted intramolecular charge-transfer (TICT) mechanism, is reported. Encapsulation in a cucurbit[7]uril host gave a 1:1 complex exhibiting a moderate emission increase due to destabilization of the TICT state inside the apolar cucurbituril cavity. A much stronger fluorescence enhancement is observed in 2:2 complexes with the larger cucurbit[8]uril, which is caused by additional con…
CCDC 1910670: Experimental Crystal Structure Determination
Related Article: Marius Gaedke, Felix Witte, Jana Anhäuser, Henrik Hupatz, Hendrik V. Schröder, Arto Valkonen, Kari Rissanen, Arne Lützen, Beate Paulus, Christoph A. Schalley |2019|Chemical Science|10|10003|doi:10.1039/C9SC03694F
CCDC 1899328: Experimental Crystal Structure Determination
Related Article: Ondřej Jurček, Rakesh Puttreddy, Filip Topić, Pia Jurček, Pezhman Zarabadi-Poor, Hendrik V. Schröder, Radek Marek, Kari Rissanen|2020|Cryst.Growth Des.|20|4193|doi:10.1021/acs.cgd.0c00532
CCDC 1957981: Experimental Crystal Structure Determination
Related Article: Fei Jia, Hendrik V. Schröder, Liu-Pan Yang, Carolina von Essen, Sebastian Sobottka, Biprajit Sarkar, Kari Rissanen, Wei Jiang, Christoph A. Schalley|2020|J.Am.Chem.Soc.|142|3306|doi:10.1021/jacs.9b11685
CCDC 938974: Experimental Crystal Structure Determination
Related Article: Lena Kaufmann, Nora L. Traulsen, Andreas Springer, Hendrik V. Schröder, Toni Mäkelä, Kari Rissanen, Christoph A. Schalley|2014|Org.Chem.Front.|1|521|doi:10.1039/C4QO00077C
CCDC 1867147: Experimental Crystal Structure Determination
Related Article: Stefan Schoder, Hendrik V. Schröder, Luca Cera, Rakesh Puttreddy, Arne Güttler, Ute Resch‐Genger, Kari Rissanen, Christoph A. Schalley|2019|Chem.-Eur.J.|25|3257|doi:10.1002/chem.201806337
CCDC 1959539: Experimental Crystal Structure Determination
Related Article: Ondřej Jurček, Rakesh Puttreddy, Filip Topić, Pia Jurček, Pezhman Zarabadi-Poor, Hendrik V. Schröder, Radek Marek, Kari Rissanen|2020|Cryst.Growth Des.|20|4193|doi:10.1021/acs.cgd.0c00532
CCDC 1581480: Experimental Crystal Structure Determination
Related Article: Hendrik V. Schröder, Felix Witte, Marius Gaedke, Sebastian Sobottka, Lisa Suntrup, Henrik Hupatz, Arto Valkonen, Beate Paulus, Kari Rissanen, Biprajit Sarkar, Christoph A. Schalley|2018|Org.Biomol.Chem.|16|2741|doi:10.1039/C8OB00415C
CCDC 1867144: Experimental Crystal Structure Determination
Related Article: Stefan Schoder, Hendrik V. Schröder, Luca Cera, Rakesh Puttreddy, Arne Güttler, Ute Resch‐Genger, Kari Rissanen, Christoph A. Schalley|2019|Chem.-Eur.J.|25|3257|doi:10.1002/chem.201806337
CCDC 1899329: Experimental Crystal Structure Determination
Related Article: Ondřej Jurček, Rakesh Puttreddy, Filip Topić, Pia Jurček, Pezhman Zarabadi-Poor, Hendrik V. Schröder, Radek Marek, Kari Rissanen|2020|Cryst.Growth Des.|20|4193|doi:10.1021/acs.cgd.0c00532
CCDC 1899330: Experimental Crystal Structure Determination
Related Article: Ondřej Jurček, Rakesh Puttreddy, Filip Topić, Pia Jurček, Pezhman Zarabadi-Poor, Hendrik V. Schröder, Radek Marek, Kari Rissanen|2020|Cryst.Growth Des.|20|4193|doi:10.1021/acs.cgd.0c00532
CCDC 1867143: Experimental Crystal Structure Determination
Related Article: Stefan Schoder, Hendrik V. Schröder, Luca Cera, Rakesh Puttreddy, Arne Güttler, Ute Resch‐Genger, Kari Rissanen, Christoph A. Schalley|2019|Chem.-Eur.J.|25|3257|doi:10.1002/chem.201806337
CCDC 1899331: Experimental Crystal Structure Determination
Related Article: Ondřej Jurček, Rakesh Puttreddy, Filip Topić, Pia Jurček, Pezhman Zarabadi-Poor, Hendrik V. Schröder, Radek Marek, Kari Rissanen|2020|Cryst.Growth Des.|20|4193|doi:10.1021/acs.cgd.0c00532
CCDC 1867145: Experimental Crystal Structure Determination
Related Article: Stefan Schoder, Hendrik V. Schröder, Luca Cera, Rakesh Puttreddy, Arne Güttler, Ute Resch‐Genger, Kari Rissanen, Christoph A. Schalley|2019|Chem.-Eur.J.|25|3257|doi:10.1002/chem.201806337
CCDC 1867146: Experimental Crystal Structure Determination
Related Article: Stefan Schoder, Hendrik V. Schröder, Luca Cera, Rakesh Puttreddy, Arne Güttler, Ute Resch‐Genger, Kari Rissanen, Christoph A. Schalley|2019|Chem.-Eur.J.|25|3257|doi:10.1002/chem.201806337
CCDC 1867142: Experimental Crystal Structure Determination
Related Article: Stefan Schoder, Hendrik V. Schröder, Luca Cera, Rakesh Puttreddy, Arne Güttler, Ute Resch‐Genger, Kari Rissanen, Christoph A. Schalley|2019|Chem.-Eur.J.|25|3257|doi:10.1002/chem.201806337
CCDC 2073308: Experimental Crystal Structure Determination
Related Article: Marius Gaedke, Henrik Hupatz, Hendrik V. Schröder, Simon Suhr, Kurt F. Hoffmann, Arto Valkonen, Biprajit Sarkar, Sebastian Riedel, Kari Rissanen, Christoph A. Schalley|2021|Org.Chem.Front.|8|3659|doi:10.1039/D1QO00503K
CCDC 1586984: Experimental Crystal Structure Determination
Related Article: Hendrik V. Schröder, Felix Witte, Marius Gaedke, Sebastian Sobottka, Lisa Suntrup, Henrik Hupatz, Arto Valkonen, Beate Paulus, Kari Rissanen, Biprajit Sarkar, Christoph A. Schalley|2018|Org.Biomol.Chem.|16|2741|doi:10.1039/C8OB00415C