Jochen Mattay

Self-Assembly of 2,8,14,20-Tetraisobutyl-5,11,17,23-tetrahydroxyresorc[4]arene

We report herein the observation of a hexameric structure of a hydroxyresorc[4]arene in the solid state, enclosing a large interior space. This artificial molecular container is stabilized only by hydrogen bonds. The tendency to form aggregates in solution is demonstrated mainly by means of ESI-MS methods.

Green photochemistry: Production of fine chemicals with sunlight

Three photochemical reactions were investigated under solar irradiation conditions with moderately concentrated sunlight: the photoacylation of naphthoquinone with butyraldehyde and the dye-sensitized photooxygenations of citronellol and 1,5-dihydroxynaphthalene, respectively. All reactions were easily performed on multigram-to-kilogram scales using cheap and commercially available starting materials, and yielded important key intermediates for industrial applications.

Interfacial electrostatics guiding the crystallization of CaCO3 underneath monolayers of calixarenes and resorcarenes

The amphiphilic octaacids rccc-4,6,10,12,16,18,22,24-octakis-O-(carboxymethyl)-2,8,14,20-tetra(n-undecyl)resorc[4]arene (1) and 5,11,17,23,29,35,41,47-octakis(1,1,3,3-tetramethylbutyl)-49,50,51,52,53,54,55,56-octa(carboxymethoxy)calix[8]arene (2) form stable monolayers at the air–water interface which induce growth of CaCO3 crystals at the monolayer–solution interface. Uniformly (012) oriented rhombohedral calcite single crystals grow underneath a monolayer of 2, whereas crystallization under a monolayer of 1 preferentially leads to formation of acicular aggregates of aragonite crystals. While polymorph selection and orientations of the CaCO3 crystals critically depend on the average charge density of the monolayer, the molecular shape and the particular Ca coordination behaviour of the amphiphiles that form the monolayer are of minor importance. CaCO3 crystal growth underneath monolayers of macrocyclic amphiphiles is briefly reviewed and the present experimental observations are compared to previous related investigations on “template-induced” biomimetic mineralization.

Selectivity and charge transfer in photoreactions of arenes with olefins1: 2, Mode of cycloaddition

Abstract An empirical rule is presented which can rationalize the modes of cycloaddition in photoreactions of arenes with olefins. This rule bases on the exciplex mechanism and on the Rehm-Weller equation of electron transfer. The correlations between the selectivities and the free enthalpies of electron transfer (ΔG) were carried out for various systems. They also include the “exceptions” according to Bryce-Smiths ΔIP-rule. Therefore, this rule which is presented here may provide a useful guide for planning syntheses.

Exohedral functionalization of [60]fullerene by [3+2] cycloadditions: Syntheses and chemical properties of triazolino-[60]fullerenes and 1,2-(3,4-dihydro-2H-pyrrolo)-[60]fullerenes

The reaction of C-60 with aryl azides 5 in dichlorobenzene at room temperature leads to isolable triazolinofullerene derivatives 6a and 6b. Photolysis of 6 selectively yields the aziridinofullerenes 7, In contrast to the photolysis the thermolysis affords the azafulleroids 8 as main product next to C-60 In addition the first photochemically induced rearrangement of azafulleroids (1,6-aza-bridged isomers) to aziridinofullerenes (1,2-aza-bridged isomers) is described. Beside aziridines 7 the photochemical reactions of azides 5 with C-60 predominantly yield one novel C-s symmetrical bisadduct, respectively. Furthermore the syntheses of symmetrical 1,2-(3.4-dihydro-2H-pyrrolo)-[60]fullerenes 12a-c by [3+2] cycloaddition of nitrile ylides ii are reported. Copyright (C) 1996 Published by Elsevier Science Ltd

Aza-dihydro[60]fullerene in the gas phase. A mass-spectrometric and quantumchemical study

Abstract A new approach to produce heterofullerenes is described. Starting from a fullerene with an intact cage which is activated by suitable exohedral functionalization, the first aza-heterofullerene is generated in the gas phase under DCI mass-spectrometric conditions. On the basis of AMI-calculations the 1,2-closed structure is proposed to be the most stable one.

Green photochemistry: solar photooxygenations with medium concentrated sunlight

The rose bengal sensitized photooxygenations of citronellol and 1,5-dihydroxynaphthalene were performed successfully under solar irradiation conditions, and complete conversions (>95%) were achieved in almost all cases in relatively short illumination times. The selected reactions were easily performed on multigram to kilogram scales using cheap and commercially available starting materials, and yielded important key-intermediates for industrial applications.

Green photochemistry: solar-chemical synthesis of Juglone with medium concentrated sunlight

Dye sensitized photooxygenations of 1,5-dihydroxynaphthalene were investigated with soluble and solid-supported sensitizers and moderately concentrated sunlight. Moderate to good yields up to 79% of 5-hydroxy-1,4-naphthoquinone (Juglone) were achieved on multiple gram-scales after just 4 h of illumination. The mild and environmentally friendly reaction conditions make this application particularly attractive for ‘green photochemistry’.

[3+2] Cycloadditions and nucleophilic additions of aziridines under CC and CN bond cleavage☆

Abstract Under PET conditions (photoinduced electron transfer) aziridines react with dipolarophiles in a [3+2] cycloaddition to form five-membered heterocycles. In this study we used mono- and disubstituted N-alkyl and N-arylaziridines. We noticed that the radical cation as intermediate reacts in a different manner to the classical azomethine ylide. Furthermore, under mild thermal conditions, aziridines react in acetonitrile in a formal [3+2] cycloaddition with activated acetylene derivatives under CN bond cleavage. Using methanol as solvent, the intermediate is trapped leading to highly substituted enamines. A mechanism for this unexpected thermal reaction is proposed.

Addition of photochemically generated acylnitrenes to C60. Synthesis of fulleroaziridines and thermal rearrangement to fullerooxazoles

The reaction of C60 to acylnitrenes 2, generated by photolysis of aroylazides 1 in dichloromethane, creates the stable fulleroaziridine derivatives 3a, 3b, 3c and 3d. The rearrangement of the fulleroaziridines 3 by boiling in tetrachloroethane leads to the formation of the corresponding fullerooxazoles 4a, 4b, 4c, and 4d. The formation of a fullerooxazole 4b was also observed by irradiation of C60 and 1b in benzene.