Abstract:Four new organic hosts are described that contain a phthalocyanine core to which four crown ether rings are attached.These hosts include a free base phthalocyanine with 18-crown-6 rings and three copper phthalocyanines with 15-crown-5, 18-crown-6, and 21-crown-7 rings. The macrocycles are synthesized from benzo crown ethers in three steps. In solution the phthalocyanines tend to form aggregates. This aggregation is affected by the polarity of the solvent and the presence of alkali-metal salts, which coordinate to the crowns. Cations with diameters that match the diameters of the crown ether rings form 4:4 host-guest complexes with the new hosts. Complexes with 8:4 host-guest stoichiometry are formed when the diameters of the cations exceed that of the crown ether rings. Binding free energies of the copper phthalocyanine hosts are presented and compared to those of benzo crown ethers. The binding profiles support the results of UV-vis experiments; i.e., that large cations induce aggregation of the macrocycles.

Abstract:We describe the synthesis and characterization of phthalocyaninato polysiloxanes substituted with 15-crown-5, 18-crown-6, and 21-crown-7 rings. The degree of polymerization of the polymer samples depends on the size of the crown ether rings and varies between 6 and 18 units. NMR spectroscopy reveals that the polysiloxanes have a rigid structure with staggered phthalocyaninato (Pc) units. The binding of alkali-metal ions to the plymers and their monomers is reported and discussed. Upon polymerization of the phthalocyaninato dihydroxysilanes the electronic conductivity increases from C to lO-'S/m. The polymer substituted with 21-crown-7 rings conducts sodium ions.Phthalocyanines (Pc's) substituted with crown ether rings are currently receiving great interest.Iq6 Recently, we reported that these molecules can be aggregated by addition of alkali-metal salts, which become complexed to the crown ether rings.lb-c Electrical measurements of the aggregated species revealed an increase in electrical conductivity that is 2-3 powers of 10 higher than that of the nonaggregated ones.In this paper we report another method of aggregating phthalocyanines.2 This method, first described by Joyner and K e n n e~,~* involves the polycondensation of a phthalocyaninato dihydroxysilane containing four crown ether rings. In this way a stacked quasi-one-dimensional arrangement of crowned Pc's is achieved in which the central silicon atoms are bridged through 02-ligands (Figure 1). These stacks are expected to transport electrons and ions in the stacking direction: electrons via the central Pc macrocycles and cations via the crown ether moieties. Such compounds when incorporated in vesicle bilayers could be used as synthetic models to mimic both electron and ion channels of natural transport systems.Substituted and unsubstituted phthalocyaninato polysiloxanes,[PcSiO],, have been studied by many scientist^.^ Unsubstituted *University of Utrecht.i Delft University of Technology.1' University of Nijmegen.

Ionic liquids [1] are among the solvents [2] which can be used by molecular designers [3] to fine tune the performance of chemical systems in order to facilitate high atom economy [4] for chemical reactions or facile separation of products from reagents or catalyst, [5] all constituting key parts of green chemistry. [6] In particular, they can provide control at the molecular level of the vapor pressure of the medium, [7] a key issue of process safety and environmental protection. The ultimate success of these solvents depends on whether they will be used commercially in small-or larger-scale applications. Of course, a profitable larger-scale process will convince others to explore and use the same or similar media for different applications. Ionic liquids are starting to leave the academic laboratories and find their way into a wide variety of industrial applications.[8] We have been investigating the mechanism of the Beckmann rearrangement of cyclohexanone oxime (1) to e-caprolactam (2) in sulfuric acid and oleum as described [9] and conclude now that the caprolactam process [10] is in fact the largest-scale industrial technology that has been using an ionic liquid, caprolactamium hydrogen sulfate (3), as the reaction medium for decades. We report here the physical characterization of this ionic liquid, including its remarkable capability to keep the vapor pressure of 12 % dissolved sulfur trioxide below 10 kPa even at 140 8C, allowing its safe use in large-scale processes for decades. The mechanism of the Beckmann rearrangement of cyclohexanone oxime (1) to e-caprolactam (2) has been also investigated in 18 O-labeled sulfuric acid, which revealed that the migration of the oxygen function is intermolecular. The cause of the accelerating effect of excess sulfur trioxide in the Beckmann rearrangement in oleum is discussed.The commercial processes of the Beckmann rearrangement of 1 to 2 are performed in the presence of oleum.[10] The reaction is carried out in the so-called "rearrangement mixture" obtained from mixing oleum with molten 1. As the reaction proceeds to complete conversion of 1 with a remarkable 99.5 % selectivity to 2, an appropriate amount of the rearrangement mixture is removed for neutralization with ammonia to produce the final product 2 and (NH 4 ) 2 SO 4 . The molar ratio of the oleum to 1, calculated as ([, is generally greater than one because the dissolved sulfur trioxide plays an important role by significantly increasing the rate of the reaction.[11] As the Beckmann rearrangement of 1 to 2 is very exothermic, [10] the control of the vapor pressure of SO 3 has therefore been a key safety issue.The reaction medium, traditionally called the rearrangement mixture, can be prepared by dissolving 2 in sulfuric acid or oleum. Importantly, note that the addition of one equivalent of 2 to 100 % sulfuric acid results in the formation of a colorless solid at room temperature, which becomes a viscous liquid around 60 8C. Although its viscosity decreases further by increasing the temperature, it was no...

The synthesis is described of a phthalocyanine that contains four 15-crown-5 rings; K+ ions induce dimerization of the phthalocyanine, whereas Li+ and ButNH3+ ions do not.We designed the polytopic ligand (2) as part of a programme aimed at the development of multifunctional catalysts and carrier systems from easily accessible host molecules. Compound (2) contains a metal centre that is complexed by a phthalocyanine ring and four crown ether binding sites. Its synthesis and binding properties are described.Benzo-15-crown-5 (1)' was brominated (Fe-Br2, solvent CH2C12) to give 4,5-dibromobenzo-15-crown-5 in 65% yield. The latter compound (1.0 mmol) was refluxed for 20 h with CuCN (5 mmol) in N , N-dimethylformamide (1.5 dm3). A small amount of pyridine (O.ldm3) was added as a catalyst. After work-up (aqueous ammonia, extraction with chloroform) the solid residue was subjected to column chromatography (neutral alumina, eluant CHC13-MeOH, 10 : 1 vh). Compound (2) was obtained as a green, almost black powder in 35% yield (m.p. > 2OO0C

ReferencesAggregation of 'crowned' phthalocyanines by metal salts increases the electrical conductivity compared to the non-aggregated phthalocyanines. In a previous paper we described the synthesis and aggregation behaviour of phthalocyanines which contain crown ether subunits, e.g. (I).4 Compound (1) forms aggreg ates in the presence of alkali metal ions5 (Figure 1). We now report that these aggregates exhibit increased electrical conductivity as compared to uncomplexed (1) and unsubsti tuted phthalocyanines.K +, R b+, and Cs+ picrate complexes of (1) were prepared by mixing the latter compound and the appropriate metal picrate in a 1:4 ratio in chloroform-methanol (1:1 v/v) and stirring at -40 °C for two days. The gre£n precipitates were isolated by filtration, washed with hot methanol and chloro form until a colourless filtrate was obtained, and dried t Present address: