In 1981, the macrocyclic methylene-bridged glycoluril hexamer (CB[6]) was dubbed "cucurbituril" by Mock and co-workers because of its resemblance to the most prominent member of the cucurbitaceae family of plants--the pumpkin. In the intervening years, the fundamental binding properties of CB[6]-high affinity, highly selective, and constrictive binding interactions--have been delineated by the pioneering work of the research groups of Mock, Kim, and Buschmann, and has led to their applications in waste-water remediation, as artificial enzymes, and as molecular switches. More recently, the cucurbit[n]uril family has grown to include homologues (CB[5]-CB[10]), derivatives, congeners, and analogues whose sizes span and exceed the range available with the alpha-, beta-, and gamma-cyclodextrins. Their shapes, solubility, and chemical functionality may now be tailored by synthetic chemistry to play a central role in molecular recognition, self-assembly, and nanotechnology. This Review focuses on the synthesis, recognition properties, and applications of these unique macrocycles.

The cucurbit[n]uril family

Cyanines during the 1990s: A Review

Ozonation of drinking water: part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine.

3.10 - Nitroxide-Mediated Polymerization

This review provides an overview of different aspects of inclusion chemistry in ordered mesoporous host materials such as MCM-41 or MCM-48 (Mobil codes). A rich field of inclusion chemistry has been explored in this context, including sorption, ion exchange, imbibition followed by reduction, grafting of reactive metal alkoxides, halides etc., grafting of silane coupling agents (sometimes followed by subsequent reactions), grafting of reactive metal complexes, and polymerization in the channels. Finally, co-condensation of reactive species during the mesopore synthesis is a method to incorporate functionality into the walls of the channel system. Important applications of these modified and functionalized systems are heterogeneous catalysis and photocatalysis involving bulky grafted catalysts and/or the conversion of large substrates. Other potential applications include ion exchange and separations, removal of heavy metals, chromatography, stabilization of quantum wires, stabilization of dyes, and polymer...

Inclusion Chemistry in Periodic Mesoporous Hosts

Spectra and rate constants of reactions were measured of chlorine and bromine atoms formed by photolysis of aqueous solutions of hypochlorous and hypobromous acids and their salts with light of wavelength 248 5 and 308 nm Chlorine and bromine atoms in aqueous solution behave like weak oxygen acids showing the pKa-values 51 and 105, respectively Exchanges of water molecules bound to the halogen atoms are fast processes

Laser Flash Photolysis of HCIO, CIO−, HBrO, and BrO− in Aqueous Solution. Reactions of Cl- and Br-Atoms

Coumarin and 6-alkylcoumarins (alkyl = C1 to C16) were photodimerized in homogeneous solvents differing in polarity and in aqueous micellar solutions. The four possible photodimers, syn head-to-head (hh), anti head-to-head, syn head-to-tail (ht), and anti head-to-tail, were identified through a combination of X-ray analysis and NMR spectroscopy. In 6-methylcoumarin the concentration-corrected dimerization (quantum) yield increases with decreasing concentration of the educt; anti-hh was formed exclusively in nonpolar solvents and upon triplet sensitization and was the main product under all conditions except for ionic micellar systems, which direct to preferred syn-hh dimerization. Long alkyl substituents, however, lead to anti-hh in polar solvents and in micelles, too. Predominating ht dimer formation was observed for nonsubstituted coumarin in polar solvents only. Thus, syn/anti and hh/ht selectivity can be steered by varying the 6-alkyl substituent. Syn-hh photodimers of 6-methylcoumarin can be photoche...

Selectivity in the photodimerization of 6-alkylcoumarins.

The photoprocesses of parent coumarin (1) and a series of 6-alkyl substituted coumarins (2–11, alkyl chain lengths between 1 and 16 C-atoms) in solution were studied by time-resolved UV-vis absorption spectroscopy The triplet properties under direct and benzophenone-sensitized excitation conditions are outlined, whereas any singlet state reactions towards photodimers are unlikely The quantum yield of intersystem crossing of 1–11 is small, Φisc = 002–005, in benzene, acetonitrile or methanol and much larger, Φisc = 01–05, in water and 2,2,2-trifluoroethanol The rate constant for intrinsic decay was found to be below 1 × 105 s−1 in most cases The observed triplet state reacts with coumarins; the rate constant for this self-quenching step is largest in aqueous solution, 3 × 109 M−1 s−1, and smallest, 3 × 107 M−1 s−1, in benzene The results for the derivatives are very similar and the main difference is a lower Φisc for 1 in aqueous solution The published product yields and patterns from preparative irradiations as a function of solvent polarity are discussed in view of the triplet properties

Photodimerization of coumarin revisited: Effects of solvent polarity on the triplet reactivity and product pattern

The kinetics of ozone formation in the photolysis of oxygen-containing solutions of HClO, ClO–, ClO–2, ClO–3, HBrO, BrO– and BrO–3 has been studied by laser flash photolysis and conventional flash photolysis. The usual assumption, that ozone only forms in the reaction of oxygen atoms in the spin-triplet ground state with molecular oxygen: O + O2→ O3 subsequent to the primary process [graphic omitted] is found to be valid for solutions at pH ⩽ 10 but not for more strongly alkaline solutions. The rate constants of the reactions of O with O2 and BrO–3 are found to be 4.0 × 109 and 1.5 × 107 dm3 mol–1 s–1, respectively. The formation of ozone in strongly alkaline solutions can be accounted for by the additional processes O–3+ XO–n– 1→ O3+ XO–n– 1 with rate constants in the range 5 × 108 to 1.5 × 109 dm3 mol–1 s–1 subsequent to O–+ O2⇌ O–3 and the primary process [graphic omitted].

Thomas Wolff

Papers

Laser Flash Photolysis of HCIO, CIO−, HBrO, and BrO− in Aqueous Solution. Reactions of Cl- and Br-Atoms

Selectivity in the photodimerization of 6-alkylcoumarins.

Photodimerization of coumarin revisited: Effects of solvent polarity on the triplet reactivity and product pattern

Ozone formation in laser flash photolysis of oxoacids and oxoanions of chlorine and bromine

Succinyl amide gemini surfactant from Adenopus breviflorus seed oil: A potential corrosion inhibitor of mild steel in acidic medium