Rhodium(III) octahedral complexes with amine and chloride ligands are the most common starting co... more Rhodium(III) octahedral complexes with amine and chloride ligands are the most common starting compounds for preparing catalytically active rhodium(I) and rhodium(III) species. Despite intensive study during the last 100 years, synthesis and crystal structures of rhodium(III) complexes were described only briefly. Some [RhClx(NH3)6-x] compounds are still unknown. In this study, available information about synthetic protocols and the crystal structures of possible [RhClx(NH3)6−x] octahedral species are summarized and critically analyzed. Unknown crystal structures of (NH4)2[Rh(NH3)Cl5], trans–[Rh(NH3)4Cl2]Cl⋅H2O, and cis–[Rh(NH3)4Cl2]Cl are reported based on high quality single crystal X-ray diffraction data. The crystal structure of [Rh(NH3)5Cl]Cl2 was redetermined. All available crystal structures with octahedral complexes [RhClx(NH3)6-x] were analyzed in terms of their packings and pseudo-translational sublattices. Pseudo-translation lattices suggest face-centered cubic and hexago...
Simvastatin is one of the most widely used active pharmaceutical ingredients for the treatment of... more Simvastatin is one of the most widely used active pharmaceutical ingredients for the treatment of hyperlipidemias. Because the compound is employed as a solid in drug formulations, particular attention should be given to the characterization of different polymorphs, their stability domains, and the nature of the phase transitions that relate them. In this work, the phase transitions delimiting the stability domains of three previously reported simvastatin forms were investigated from structural, energetics, and dynamical points of view based on single crystal X-ray diffraction (SCXRD), hot stage microscopy (HSM), and differential scanning calorimetry (DSC) experiments (conventional scans and heat capacity measurements), complemented with molecular dynamics (MD) simulations. Previous assignments of the crystal forms were confirmed by SCXRD: forms I and II were found to be orthorhombic ( P222, Z'/ Z = 1/4) and form III was monoclinic ( P2, Z'/ Z = 2/4). The obtained results fu...
Development of new radiopharmaceuticals based on rhenium-188 depends on finding appropriate ligan... more Development of new radiopharmaceuticals based on rhenium-188 depends on finding appropriate ligands able to give complexes with high in vivo stability. Rhenium(III) mixed-ligand complexes with tetradentate/monodentate ('4 + 1') coordination of the general formula [Re(NS 3)(PRR′R′′)] (NS 3) tris-(2-mercaptoethyl)amine and derivatives thereof, PRR′R′′) phosphorus(III) ligands) appear to be among the promising tools to achieve this goal. According to this approach, we synthesized and characterized a series of rhenium model complexes. In vitro stabilities of the corresponding rhenium-188 complexes were determined by incubating 2-3 MBq or alternatively 37 MBq of the complexes in phosphate buffer, human plasma, and rat plasma, respectively, at 22°C or 37°C, followed by checking the amount of 188 ReO 4formed after 1 h, 24, and 48 h by thin-layer chromatography. The rate of perrhenate formation varied over a wide range, depending primarily on the nature of the phosphorus(III) ligand. Physicochemical parameters of the corresponding nonradioactive rhenium complexes were analyzed in detail to find out the factors influencing their different stability and furthermore to design new substitution-inert '4 + 1' complexes. Tolman's cone angle of phosphorus(III) ligands and the lipophilic character of the inner coordination sphere were found to be crucial factors to build up stable rhenium '4 + 1' complexes. Additional information useful to describe electronic and steric properties of these compounds were selected from electronic spectra (wavelength of the RefS charge-transfer band), cyclovoltammetric measurements (E°of the Re III /Re IV couple), and NMR investigations (31 P chemical shift of coordinated P(III) ligands).
The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yie... more The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yields the novel mononuclear [Cu(pyterpy) 2 ](PF 6) 2 complex. The crystal structure shows that the Cu(II) center is coordinated by the terpyridine domains of both pyterpy molecules, while the pyridyl tails remain uncoordinated. Intermolecular p-p stacking interactions between the cations in the crystal result in the formation of alternating 1-D linear channels which run in perpendicular directions.
The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yie... more The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yields the novel mononuclear [Cu(pyterpy) 2 ](PF 6) 2 complex. The crystal structure shows that the Cu(II) center is coordinated by the terpyridine domains of both pyterpy molecules, while the pyridyl tails remain uncoordinated. Intermolecular p-p stacking interactions between the cations in the crystal result in the formation of alternating 1-D linear channels which run in perpendicular directions.
In our laboratory more than 100,000 urinary calculi have been analysed since 1972. Amongst this h... more In our laboratory more than 100,000 urinary calculi have been analysed since 1972. Amongst this huge sample, 15 specimens originating from a total of eight patients were observed showing similar characteristics but escaping unambiguous identification with any of the substances that have been described so far in urinary concrements. Therefore, the unknown substance was submitted to a more extended analytical regimen. Structural analysis by x-ray crystallography turned out to be most successful, identifying the unknown material as uric acid monohydrate. Uric acid monohydrate crystallizes in the monocline space group P2(1)/c. Within the crystal, uric acid and water molecules form continuous layers by hydrogen bonds. This is in contrast to uric acid in its water free and its dihydrate forms, which both crystallize by forming 3-dimensional networks To the best of our knowledge , the existence of a monohydrate form of uric acid has not been reported so far. Accordingly, this is the first ...
The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields fu... more The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields functional bispidines enabling convenient functionalization for targeted imaging. The BODIPY-substituted bispidine 3 combines a coordination site for metal ions, such as radioactive (64) Cu(II) , with a fluorescent unit. Product 3 was thoroughly characterized by standard analytical methods, single crystal X-ray diffraction, radiolabeling, and photophysical analysis. The luminescence of ligand 3 was found to be strongly dependent on metal ion coordination: Cu(II) quenches the BODIPY fluorescence, whereas Ni(II) and Zn(II) ions do not affect it. It follows that, in imaging applications with the positron emitter (64) Cu(II) , residues of its origin from enriched (64) Ni and the decay products (64) Ni(II) and (64) Zn(II) , efficiently restore the fluorescence of the ligand. This allows for monitoring of the emitted radiation as well as the fluorescence signal. The stability of the (64) Cu(II) 3 complex is investigated by transmetalation experiments with Zn(II) and Ni(II) , using fluorescence and radioactivity detection, and the results confirm the high stability of (64) Cu(II) 3. In addition, metal complexes of ligand 3 with the lanthanide ions Tb(III) , Eu(III) , and Nd(III) are shown to exhibit emission of the BODIPY ligand and the lanthanide ion, thus enabling dual emission detection.
A novel synthetic strategy toward highly fluorinated BODIPY dyes with exceptional photostabilitie... more A novel synthetic strategy toward highly fluorinated BODIPY dyes with exceptional photostabilities relying on sustainable gold catalysis has been developed.
Retrieving quantitative molecular information from macroscopic areas in a reliable manner at micr... more Retrieving quantitative molecular information from macroscopic areas in a reliable manner at micrometric resolution is a challenging task, yet essential for a better understanding and control of the assembly of (bio)chemical entities on a functional surface. In their Full Paper, Knut Rurack and co-workers introduce fluorine-containing moieties to boron-dipyrromethene (BODIPY) dyes, thus making them versatile probes for dual-method surface analysis (p. 25 ff.). The cover picture shows a bright fluorescent dye (green halo) containing a high number of fluorine atoms (blue) for the assessment of reactive amino groups on a glass surface by two complementary surface analytical techniques, non-destructive fluorescence scanning and quantitatively traceable X-ray photoelectron spectroscopy (XPS), both applied to the same individual samples.
The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) de... more The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) derivatives with benzimidazole and imidazole donor groups at the N-3 position of the bispidine skeleton and their copper(II) complexes are reported. The impact of the hetaryl substituents on the configurational isomerism of piperidones and their corresponding bispidones has been studied by NMR spectroscopy, revealing the exclusive appearance in the enol form for the piperidones in solution and the trans-configuration regarding the two pyridyl substituents, as well as the sole formation of the unsymmetric exo-endo isomers for the corresponding bispidones. Thus, the bispidones are preorganized ligands for building pentacoordinated complexes, confirmed by the preparation and characterization of the corresponding Cu(II) complexes. Of the di-pyridyl piperidones with benzimidazole and imidazole substituents, and of the Cu(II) complex of the benzimidazole-containing bispidone, crystals have become available for the analysis by X-ray diffraction, showing that the piperidones form the enol tautomers also in the solid state.
A robust and re-usable dipstick-type fluorescent pH sensor for the alkaline pH range was develope... more A robust and re-usable dipstick-type fluorescent pH sensor for the alkaline pH range was developed by embedding a brightly fluorescent boron-dipyrromethene (BODIPY) dye bearing an acidic phenol moiety within a polyurethane matrix immobilized on a 3D epoxy-functionalized polymer support. The sensor strip has a dynamic working range of pH 10.0-13.1, i.e., operates in strongly basic media where pH glass electrodes can suffer from alkaline errors, and tolerates a high electrolyte background such as simulated seawater. This work describes the preparation of the sensing material and provides insight into the features that a hydrogel sensing membrane can bestow on an embedded pH-responsive dye by means of optical spectroscopic investigations. 65 Materials and Methods All reagents were obtained from commercial suppliers and were used without further purification unless otherwise indicated. All air-and moisture-sensitive reactions were carried out under argon atmosphere in oven-dried glassware. TLC was performed on 70 Merck Silica Gel 60 F254 TLC plates with a fluorescent indicator for 254 nm excitation. Compounds were visualized under UV light of 254 nm. Column chromatography was carried out with Merck Silica gel 60 (0.040-0.063 mm) using dichloromethane (CH 2 Cl 2) as eluent. NMR spectra were recorded on a 400 MHz 75 (100.6 MHz for 13 C) Bruker AV 400 or on a 300 MHz (75.6 MHZ for 13 C) Bruker DPX 300 spectrometer at 27 °C using residual protonated solvent signals as internal standard (1 H: δ(CDCl 3) = 7.26 ppm and 13 C: δ(CDCl 3) = 77.16 ppm).
Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with i... more Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with increasing pH. The resulting amorphous and partly crystalline oxydydroxides AnO n (OH) 4−2n •xH 2 O can usually be observed as colloids above the An(IV) solubility limit. The aging process of such colloids results in crystalline AnO 2. The presence of carboxylates in the solution prevents the occurrence of such colloids by formation of polynuclear complexes through a competing reaction between hydrolysis and ligation. The majority of recently described carboxylates reveals a hexanuclear core of [An 6 (µ 3-O) 4 (µ 3-OH) 4 ] 12+ terminated by 12 carboxylate ligands. We found that the An(IV) carboxylate solution species remain often preserved in crystalline state. The An(IV) carboxylates show An−An distances which are ~ 0.03 Å shorter than the An−An distances in AnO 2 like colloids. The difference in the distances could be used to identify such species in solution.
ABSTRACT A systematic structural investigation of R-phenyl-substituted 2,2': 6', ... more ABSTRACT A systematic structural investigation of R-phenyl-substituted 2,2': 6', 2 ''-terpyridines, a family of mono- and bifunctional charge transfer (CT)-operated fluorescent reporters for protons and metal ions, is presented. These molecules are equipped with non-binding and analyte coordinating donor substituents R (R = CF3, H, OMe, OH, DMA, A15C5 equaling monoaza-15-crown-5) of various donor strength and display CT-controlled spectroscopic properties and communication of analyte-receptor interactions. The crystal structures of the neutral fluorescent probes are compared to the structures of their terpyridine-alkylated or -protonated counterparts that represent model systems for acceptor protonation or cation coordination. The aim is here a better understanding of the complexation-induced structural and spectroscopic changes and the identification of common packing motifs of bpb-R thereby taking into account the importance of terpyridine building blocks for the construction of supramolecular systems and coordination arrays revealing pi-pi interactions. (c) 2007 Elsevier B.V. All rights reserved.
The main component of this program is a simultaneous representation of the unit cell and the calc... more The main component of this program is a simultaneous representation of the unit cell and the calculated powder pattern. It allows the manipulation of the crystal structure by moving selected atoms of the asymmetric unit. The resulting powder pattern can be directly compared to experimental data in order to obtain reliable starting values for further computations in refinement programs.
New oxorhenium complexes with 2-(diphenylphosphanyl)-N-(2-thioethyl)benzamide (H 2 PNS) and trime... more New oxorhenium complexes with 2-(diphenylphosphanyl)-N-(2-thioethyl)benzamide (H 2 PNS) and trimethyl-, triethyl-and triphenyl-hydroxyl silylated monodentate thiols are reported. These new complexes have been prepared by reacting [N n Bu 4 ][Re(O)Cl 4 ] with the tridentate H 2 PNS and the corresponding silylated thiol at room temperature. The characterization of the complexes involved elemental analysis, 31 P and 1 H NMR spectroscopies and X-ray crystallographic analysis for the triethyl-silylated Re complex.
Two new octahedral cluster complexes-[Re 6 S 8 (3,5-Me 2 PzH) 6 ]Br 2 AE 2(3,5-Me 2 PzH) (1) and ... more Two new octahedral cluster complexes-[Re 6 S 8 (3,5-Me 2 PzH) 6 ]Br 2 AE 2(3,5-Me 2 PzH) (1) and [Re 6 Se 8 (3,5-Me 2 PzH) 6 ]Br 2 AE 2(3,5-Me 2 PzH) (2), where 3,5-Me 2 PzH is 3,5-dimethylpyrazole, have been synthesized using reaction of rhenium chalcobromide complexes Cs 4 [Re 6 S 8 Br 6 ] AE 2H 2 O and Cs 3 [Re 6 Se 8 Br 6 ] AE H 2 O, respectively, with molten 3,5-dimethylpyrazole. Both compounds synthesized were characterized by X-ray single-crystal diffraction and chemical analysis, IR and luminescent spectra.
... Hilmar A. Stecher,t and Arnold L. Rheingoldt Received June 16, 1991 The reaction of C ~ ( OC ... more ... Hilmar A. Stecher,t and Arnold L. Rheingoldt Received June 16, 1991 The reaction of C ~ ( OC ' BU ~ ) ~ (1) with the following oxidants has been studied ... Either species (or both) may react with the tert-butoxyl radical to form the ceri-um(1V) mixed alkoxide 3 (eq 4). [C~(OC'BU ...
Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solutio... more Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution and the solid-state structures are surprisingly different. The species in aqueous solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) formate shows only mononuclear complexes, which is in agreement with the predicted mononuclear species of Ce(HCOO)(2+) and Ce(HCOO)2(+). In contrast, Ce(IV) formate forms in aqueous solution a stable hexanuclear complex of [Ce6(μ3-O)4(μ3-OH)4(HCOO)x(NO3)y](12-x-y). The structural differences reflect the different influence of hydrolysis, which is weak for Ce(III) and strong for Ce(IV). Hydrolysis of Ce(IV) ions causes initial polymerization while complexation through HCOO(-) results in 12 chelate rings stabilizing the hexanuclear Ce(IV) complex. Crystals were grown from the above-mentioned solutions. Two crystal structures of Ce(IV) formate were determined. Both form a hexanuclear complex with a [Ce6(μ3-O)4(μ3-OH)4](12+) core in aqueous HNO3/HCOOH solution. The pH titration with NaOH resulted in a structure with the composition [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)2(H2O)3]·(H2O)9.5, while the pH adjustment with NH3 resulted in [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)4]·(NO3)3(NH4)5(H2O)5. Furthermore, the crystal structure of Ce(III) formate, Ce(HCOO)3, was determined. The coordination polyhedron is a tricapped trigonal prism which is formed exclusively by nine HCOO(-) ligands. The hexanuclear Ce(IV) formate species from aqueous solution is widely preserved in the crystal structure, whereas the mononuclear solution species of Ce(III) formate undergoes a polymerization during the crystallization process.
Rhodium(III) octahedral complexes with amine and chloride ligands are the most common starting co... more Rhodium(III) octahedral complexes with amine and chloride ligands are the most common starting compounds for preparing catalytically active rhodium(I) and rhodium(III) species. Despite intensive study during the last 100 years, synthesis and crystal structures of rhodium(III) complexes were described only briefly. Some [RhClx(NH3)6-x] compounds are still unknown. In this study, available information about synthetic protocols and the crystal structures of possible [RhClx(NH3)6−x] octahedral species are summarized and critically analyzed. Unknown crystal structures of (NH4)2[Rh(NH3)Cl5], trans–[Rh(NH3)4Cl2]Cl⋅H2O, and cis–[Rh(NH3)4Cl2]Cl are reported based on high quality single crystal X-ray diffraction data. The crystal structure of [Rh(NH3)5Cl]Cl2 was redetermined. All available crystal structures with octahedral complexes [RhClx(NH3)6-x] were analyzed in terms of their packings and pseudo-translational sublattices. Pseudo-translation lattices suggest face-centered cubic and hexago...
Simvastatin is one of the most widely used active pharmaceutical ingredients for the treatment of... more Simvastatin is one of the most widely used active pharmaceutical ingredients for the treatment of hyperlipidemias. Because the compound is employed as a solid in drug formulations, particular attention should be given to the characterization of different polymorphs, their stability domains, and the nature of the phase transitions that relate them. In this work, the phase transitions delimiting the stability domains of three previously reported simvastatin forms were investigated from structural, energetics, and dynamical points of view based on single crystal X-ray diffraction (SCXRD), hot stage microscopy (HSM), and differential scanning calorimetry (DSC) experiments (conventional scans and heat capacity measurements), complemented with molecular dynamics (MD) simulations. Previous assignments of the crystal forms were confirmed by SCXRD: forms I and II were found to be orthorhombic ( P222, Z'/ Z = 1/4) and form III was monoclinic ( P2, Z'/ Z = 2/4). The obtained results fu...
Development of new radiopharmaceuticals based on rhenium-188 depends on finding appropriate ligan... more Development of new radiopharmaceuticals based on rhenium-188 depends on finding appropriate ligands able to give complexes with high in vivo stability. Rhenium(III) mixed-ligand complexes with tetradentate/monodentate ('4 + 1') coordination of the general formula [Re(NS 3)(PRR′R′′)] (NS 3) tris-(2-mercaptoethyl)amine and derivatives thereof, PRR′R′′) phosphorus(III) ligands) appear to be among the promising tools to achieve this goal. According to this approach, we synthesized and characterized a series of rhenium model complexes. In vitro stabilities of the corresponding rhenium-188 complexes were determined by incubating 2-3 MBq or alternatively 37 MBq of the complexes in phosphate buffer, human plasma, and rat plasma, respectively, at 22°C or 37°C, followed by checking the amount of 188 ReO 4formed after 1 h, 24, and 48 h by thin-layer chromatography. The rate of perrhenate formation varied over a wide range, depending primarily on the nature of the phosphorus(III) ligand. Physicochemical parameters of the corresponding nonradioactive rhenium complexes were analyzed in detail to find out the factors influencing their different stability and furthermore to design new substitution-inert '4 + 1' complexes. Tolman's cone angle of phosphorus(III) ligands and the lipophilic character of the inner coordination sphere were found to be crucial factors to build up stable rhenium '4 + 1' complexes. Additional information useful to describe electronic and steric properties of these compounds were selected from electronic spectra (wavelength of the RefS charge-transfer band), cyclovoltammetric measurements (E°of the Re III /Re IV couple), and NMR investigations (31 P chemical shift of coordinated P(III) ligands).
The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yie... more The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yields the novel mononuclear [Cu(pyterpy) 2 ](PF 6) 2 complex. The crystal structure shows that the Cu(II) center is coordinated by the terpyridine domains of both pyterpy molecules, while the pyridyl tails remain uncoordinated. Intermolecular p-p stacking interactions between the cations in the crystal result in the formation of alternating 1-D linear channels which run in perpendicular directions.
The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yie... more The reaction of 4 0-(4 0 0 0-pyridyl)-2,2 0 :6 0 ,2 0 0-terpyridine (pyterpy) with copper(II) yields the novel mononuclear [Cu(pyterpy) 2 ](PF 6) 2 complex. The crystal structure shows that the Cu(II) center is coordinated by the terpyridine domains of both pyterpy molecules, while the pyridyl tails remain uncoordinated. Intermolecular p-p stacking interactions between the cations in the crystal result in the formation of alternating 1-D linear channels which run in perpendicular directions.
In our laboratory more than 100,000 urinary calculi have been analysed since 1972. Amongst this h... more In our laboratory more than 100,000 urinary calculi have been analysed since 1972. Amongst this huge sample, 15 specimens originating from a total of eight patients were observed showing similar characteristics but escaping unambiguous identification with any of the substances that have been described so far in urinary concrements. Therefore, the unknown substance was submitted to a more extended analytical regimen. Structural analysis by x-ray crystallography turned out to be most successful, identifying the unknown material as uric acid monohydrate. Uric acid monohydrate crystallizes in the monocline space group P2(1)/c. Within the crystal, uric acid and water molecules form continuous layers by hydrogen bonds. This is in contrast to uric acid in its water free and its dihydrate forms, which both crystallize by forming 3-dimensional networks To the best of our knowledge , the existence of a monohydrate form of uric acid has not been reported so far. Accordingly, this is the first ...
The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields fu... more The efficient transformation of the hexadentate bispidinol 1 into carbamate derivatives yields functional bispidines enabling convenient functionalization for targeted imaging. The BODIPY-substituted bispidine 3 combines a coordination site for metal ions, such as radioactive (64) Cu(II) , with a fluorescent unit. Product 3 was thoroughly characterized by standard analytical methods, single crystal X-ray diffraction, radiolabeling, and photophysical analysis. The luminescence of ligand 3 was found to be strongly dependent on metal ion coordination: Cu(II) quenches the BODIPY fluorescence, whereas Ni(II) and Zn(II) ions do not affect it. It follows that, in imaging applications with the positron emitter (64) Cu(II) , residues of its origin from enriched (64) Ni and the decay products (64) Ni(II) and (64) Zn(II) , efficiently restore the fluorescence of the ligand. This allows for monitoring of the emitted radiation as well as the fluorescence signal. The stability of the (64) Cu(II) 3 complex is investigated by transmetalation experiments with Zn(II) and Ni(II) , using fluorescence and radioactivity detection, and the results confirm the high stability of (64) Cu(II) 3. In addition, metal complexes of ligand 3 with the lanthanide ions Tb(III) , Eu(III) , and Nd(III) are shown to exhibit emission of the BODIPY ligand and the lanthanide ion, thus enabling dual emission detection.
A novel synthetic strategy toward highly fluorinated BODIPY dyes with exceptional photostabilitie... more A novel synthetic strategy toward highly fluorinated BODIPY dyes with exceptional photostabilities relying on sustainable gold catalysis has been developed.
Retrieving quantitative molecular information from macroscopic areas in a reliable manner at micr... more Retrieving quantitative molecular information from macroscopic areas in a reliable manner at micrometric resolution is a challenging task, yet essential for a better understanding and control of the assembly of (bio)chemical entities on a functional surface. In their Full Paper, Knut Rurack and co-workers introduce fluorine-containing moieties to boron-dipyrromethene (BODIPY) dyes, thus making them versatile probes for dual-method surface analysis (p. 25 ff.). The cover picture shows a bright fluorescent dye (green halo) containing a high number of fluorine atoms (blue) for the assessment of reactive amino groups on a glass surface by two complementary surface analytical techniques, non-destructive fluorescence scanning and quantitatively traceable X-ray photoelectron spectroscopy (XPS), both applied to the same individual samples.
The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) de... more The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) derivatives with benzimidazole and imidazole donor groups at the N-3 position of the bispidine skeleton and their copper(II) complexes are reported. The impact of the hetaryl substituents on the configurational isomerism of piperidones and their corresponding bispidones has been studied by NMR spectroscopy, revealing the exclusive appearance in the enol form for the piperidones in solution and the trans-configuration regarding the two pyridyl substituents, as well as the sole formation of the unsymmetric exo-endo isomers for the corresponding bispidones. Thus, the bispidones are preorganized ligands for building pentacoordinated complexes, confirmed by the preparation and characterization of the corresponding Cu(II) complexes. Of the di-pyridyl piperidones with benzimidazole and imidazole substituents, and of the Cu(II) complex of the benzimidazole-containing bispidone, crystals have become available for the analysis by X-ray diffraction, showing that the piperidones form the enol tautomers also in the solid state.
A robust and re-usable dipstick-type fluorescent pH sensor for the alkaline pH range was develope... more A robust and re-usable dipstick-type fluorescent pH sensor for the alkaline pH range was developed by embedding a brightly fluorescent boron-dipyrromethene (BODIPY) dye bearing an acidic phenol moiety within a polyurethane matrix immobilized on a 3D epoxy-functionalized polymer support. The sensor strip has a dynamic working range of pH 10.0-13.1, i.e., operates in strongly basic media where pH glass electrodes can suffer from alkaline errors, and tolerates a high electrolyte background such as simulated seawater. This work describes the preparation of the sensing material and provides insight into the features that a hydrogel sensing membrane can bestow on an embedded pH-responsive dye by means of optical spectroscopic investigations. 65 Materials and Methods All reagents were obtained from commercial suppliers and were used without further purification unless otherwise indicated. All air-and moisture-sensitive reactions were carried out under argon atmosphere in oven-dried glassware. TLC was performed on 70 Merck Silica Gel 60 F254 TLC plates with a fluorescent indicator for 254 nm excitation. Compounds were visualized under UV light of 254 nm. Column chromatography was carried out with Merck Silica gel 60 (0.040-0.063 mm) using dichloromethane (CH 2 Cl 2) as eluent. NMR spectra were recorded on a 400 MHz 75 (100.6 MHz for 13 C) Bruker AV 400 or on a 300 MHz (75.6 MHZ for 13 C) Bruker DPX 300 spectrometer at 27 °C using residual protonated solvent signals as internal standard (1 H: δ(CDCl 3) = 7.26 ppm and 13 C: δ(CDCl 3) = 77.16 ppm).
Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with i... more Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with increasing pH. The resulting amorphous and partly crystalline oxydydroxides AnO n (OH) 4−2n •xH 2 O can usually be observed as colloids above the An(IV) solubility limit. The aging process of such colloids results in crystalline AnO 2. The presence of carboxylates in the solution prevents the occurrence of such colloids by formation of polynuclear complexes through a competing reaction between hydrolysis and ligation. The majority of recently described carboxylates reveals a hexanuclear core of [An 6 (µ 3-O) 4 (µ 3-OH) 4 ] 12+ terminated by 12 carboxylate ligands. We found that the An(IV) carboxylate solution species remain often preserved in crystalline state. The An(IV) carboxylates show An−An distances which are ~ 0.03 Å shorter than the An−An distances in AnO 2 like colloids. The difference in the distances could be used to identify such species in solution.
ABSTRACT A systematic structural investigation of R-phenyl-substituted 2,2': 6', ... more ABSTRACT A systematic structural investigation of R-phenyl-substituted 2,2': 6', 2 ''-terpyridines, a family of mono- and bifunctional charge transfer (CT)-operated fluorescent reporters for protons and metal ions, is presented. These molecules are equipped with non-binding and analyte coordinating donor substituents R (R = CF3, H, OMe, OH, DMA, A15C5 equaling monoaza-15-crown-5) of various donor strength and display CT-controlled spectroscopic properties and communication of analyte-receptor interactions. The crystal structures of the neutral fluorescent probes are compared to the structures of their terpyridine-alkylated or -protonated counterparts that represent model systems for acceptor protonation or cation coordination. The aim is here a better understanding of the complexation-induced structural and spectroscopic changes and the identification of common packing motifs of bpb-R thereby taking into account the importance of terpyridine building blocks for the construction of supramolecular systems and coordination arrays revealing pi-pi interactions. (c) 2007 Elsevier B.V. All rights reserved.
The main component of this program is a simultaneous representation of the unit cell and the calc... more The main component of this program is a simultaneous representation of the unit cell and the calculated powder pattern. It allows the manipulation of the crystal structure by moving selected atoms of the asymmetric unit. The resulting powder pattern can be directly compared to experimental data in order to obtain reliable starting values for further computations in refinement programs.
New oxorhenium complexes with 2-(diphenylphosphanyl)-N-(2-thioethyl)benzamide (H 2 PNS) and trime... more New oxorhenium complexes with 2-(diphenylphosphanyl)-N-(2-thioethyl)benzamide (H 2 PNS) and trimethyl-, triethyl-and triphenyl-hydroxyl silylated monodentate thiols are reported. These new complexes have been prepared by reacting [N n Bu 4 ][Re(O)Cl 4 ] with the tridentate H 2 PNS and the corresponding silylated thiol at room temperature. The characterization of the complexes involved elemental analysis, 31 P and 1 H NMR spectroscopies and X-ray crystallographic analysis for the triethyl-silylated Re complex.
Two new octahedral cluster complexes-[Re 6 S 8 (3,5-Me 2 PzH) 6 ]Br 2 AE 2(3,5-Me 2 PzH) (1) and ... more Two new octahedral cluster complexes-[Re 6 S 8 (3,5-Me 2 PzH) 6 ]Br 2 AE 2(3,5-Me 2 PzH) (1) and [Re 6 Se 8 (3,5-Me 2 PzH) 6 ]Br 2 AE 2(3,5-Me 2 PzH) (2), where 3,5-Me 2 PzH is 3,5-dimethylpyrazole, have been synthesized using reaction of rhenium chalcobromide complexes Cs 4 [Re 6 S 8 Br 6 ] AE 2H 2 O and Cs 3 [Re 6 Se 8 Br 6 ] AE H 2 O, respectively, with molten 3,5-dimethylpyrazole. Both compounds synthesized were characterized by X-ray single-crystal diffraction and chemical analysis, IR and luminescent spectra.
... Hilmar A. Stecher,t and Arnold L. Rheingoldt Received June 16, 1991 The reaction of C ~ ( OC ... more ... Hilmar A. Stecher,t and Arnold L. Rheingoldt Received June 16, 1991 The reaction of C ~ ( OC ' BU ~ ) ~ (1) with the following oxidants has been studied ... Either species (or both) may react with the tert-butoxyl radical to form the ceri-um(1V) mixed alkoxide 3 (eq 4). [C~(OC'BU ...
Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solutio... more Cerium(III) and cerium(IV) both form formate complexes. However, their species in aqueous solution and the solid-state structures are surprisingly different. The species in aqueous solutions were investigated with Ce K-edge EXAFS spectroscopy. Ce(III) formate shows only mononuclear complexes, which is in agreement with the predicted mononuclear species of Ce(HCOO)(2+) and Ce(HCOO)2(+). In contrast, Ce(IV) formate forms in aqueous solution a stable hexanuclear complex of [Ce6(μ3-O)4(μ3-OH)4(HCOO)x(NO3)y](12-x-y). The structural differences reflect the different influence of hydrolysis, which is weak for Ce(III) and strong for Ce(IV). Hydrolysis of Ce(IV) ions causes initial polymerization while complexation through HCOO(-) results in 12 chelate rings stabilizing the hexanuclear Ce(IV) complex. Crystals were grown from the above-mentioned solutions. Two crystal structures of Ce(IV) formate were determined. Both form a hexanuclear complex with a [Ce6(μ3-O)4(μ3-OH)4](12+) core in aqueous HNO3/HCOOH solution. The pH titration with NaOH resulted in a structure with the composition [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)2(H2O)3]·(H2O)9.5, while the pH adjustment with NH3 resulted in [Ce6(μ3-O)4(μ3-OH)4(HCOO)10(NO3)4]·(NO3)3(NH4)5(H2O)5. Furthermore, the crystal structure of Ce(III) formate, Ce(HCOO)3, was determined. The coordination polyhedron is a tricapped trigonal prism which is formed exclusively by nine HCOO(-) ligands. The hexanuclear Ce(IV) formate species from aqueous solution is widely preserved in the crystal structure, whereas the mononuclear solution species of Ce(III) formate undergoes a polymerization during the crystallization process.
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