The first three representatives of the new family of oxacyclophanes incorporating two 2,7-dioxyfluorenone fragments, connected by [-CH(2)CH(2)O-](m) spacers (m=2-4), have been synthesized. The yield of the smallest oxacyclophane (m=2) is considerably higher with respect to the larger ones (m=3 and m=4), which are formed in comparable yields. Molecular modeling and NMR spectra analysis of the model compounds suggest that an essential difference in oxacyclophanes yields is caused by formation of quasi-cyclic intermediates, which are preorganized for macrocyclization owing to intramolecular pi-pi stacking interactions between the fluorenone units. The solid-state structures of these oxacyclophanes exhibit intra- and intermolecular pi-pi stacking interactions that dictate their rectangular shape in the fluorenone backbone and crystal packing of the molecules with the parallel or T-shape arrangement. The crystal packing in all cases is also sustained by weak C--HO hydrogen bonds. FAB mass spectral analysis of mixtures of the larger oxacyclophanes (m=3 and m=4) and a paraquat moiety revealed peaks corresponding to the loss of one and two PF(6) (-) counterions from the 1:1 complexes formed. However, no signals were observed for complexes of the paraquat moiety with the smaller oxacyclophane (m=2). Computer molecular modeling of complexes revealed a pseudorotaxane-like incorporation of the paraquat unit, sandwiched within a macrocyclic cavity between the almost parallel-aligned fluorenone rings of the larger oxacyclophanes (m=3 and m=4). In contrast to this, only external complexes of the smallest oxacyclophane (m=2) with a paraquat unit have been found in the energy window of 10 kcal mol(-1).

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A new family of crownophanes containing the fluorenone and naphthalene fragments linked by oligo(oxyethylene) bridges were synthesized. Reactions of these ligands with the paraquat dication gave inclusion complexes of the pseudorotaxane type that were detected by FAB mass spectrometry, 1 H NMR spectroscopy, and electronic absorption spectroscopy.Design, synthesis, and application of various macro cyclic receptors that can selectively discriminate between metal ions, anions, and organic molecules belong to the main problems of the chemistry of "guest-host" com plexes. Cyclophanes, which are macrocycles containing two or more aromatic fragments linked by various bridges, hold a central position among such receptors. 1-6 The size, shape, charge, and hydrophobicity of a cyclophane, as well as its tendency toward various intermolecular in teractions with a guest molecule, can be easily changed by introduction in the receptor structure of rationally se lected aromatic fragments, bridges between them, and functional groups, which allows effective control of its complexing properties. Because of this, cyclophanes are widely used in membrane transport and as catalysts, sen sors, and components of catenanes and rotaxanes that are prototypes of molecular machines and nanoelectronic devices. 7-15Recently, 16-22 we have described the syntheses and properties of first representatives of fluorenonophanes containing two fluorenone fragments or the fluorenone and stilbene fragments linked by flexible polyether chains or conformationally rigid p xylylene bridges. We have demonstrated that fluorenonophanes form stable inclu sion complexes with electron deficient organic mol ecules 16-20 and are promising templates for self assembly of [2]catenanes on their basis. 21,22Here we describe the synthesis and properties of new crownophanes containing the fluorenone and naphtha lene fragments connected by oligo(oxyethylene) chains with different lengths.Crownophanes 1a-d were obtained as shown in Scheme 1.Alkylation of 2,7 dihydroxy 9H fluoren 9 one 2 23 with oligo(ethylene glycol) chlorohydrins 3a-d in DMF in the presence of K 2 CO 3 or in EtOH in the presence of KOH gave diols 4a-c or 4d in 78-80% yields. Reactions of these diols with p toluenesulfonyl chloride in a mixture of 1,4 dioxane and chloroform in the presence of Et 3 N at 0-5 °C for 30 h afforded ditosylates 5a-d in good yields (70-88%). The latter reacted with 1,5 dihydroxy naphthalene 6 at high dilution in DMF in the presence of K 2 CO 3 . After workup of the reaction mixture and puri fication by column chromatography, we obtained fluore none containing crownophanes 1a-d in moderate yields. The yield of the smallest crownophane 1a was low; the yields of crownophanes 1b-d were virtually independent of the ring size.The 1 H NMR spectra of crownophanes 1a-d show a set of signals at δ 3.65-4.38, which are typical of oligo(ethylene glycol) fragments, a characteristic set of signals (two doublets and a doublet of doublets) for the fluorenone protons, and a triplet and two doublets ...

The purpose of the study was a comparative research in the possibility of using the radiopharmaceuticals 99m Tc-Al 2 O 3 and 99m Tc-Nanocis for visualizing sentinel lymph nodes. The measurement of the sizes of 99m-Al 2 O 3 and 99m-Nanocis colloidal particles was performed in seven series of radiopharmaceuticals. The pharmacokinetics of 99m-Al 2 O 3 and 99m-Nanocis was researched on 50 white male rats. The possibility of the use of 99m-Al 2 O 3 and 99m-Nanocis for lymphoscintigraphy was studied in the experiments on 12 white male rats. The average dynamic diameter of the sol particle was 52-77 nm for 99m-Al 2 O 3 and 16.7-24.5 nm for 99m-Nanocis. Radiopharmaceuticals accumulated in the inguinal lymph node in 1 hour after administration; the average uptake of 99m Tc-Al 2 O 3 was 8.6% in it, and the accumulation of 99m Tc-Nanocis was significantly lower-1.8% (p < 0.05). In all study points the average uptake of 99m Tc-Al 2 O 3 in the lymph node was significantly higher than 99m Tc-Nanocis accumulation. The results of dynamic scintigraphic studies in rats showed that 99m Tc-Al 2 O 3 and 99m Tc-Nanocis actively accumulated into the lymphatic system. By using 99m Tc-Al 2 O 3 inguinal lymph node was determined in 5 minutes after injection and clearly visualized in all the animals in the 15th minute, when the accumulation became more than 1% of the administered dose. Further observation indicated that the 99m Tc-Al 2 O 3 accumulation reached a plateau in a lymph node (average 10.5%) during 2-hour study and then its accumulation remained practically at the same level, slightly increasing to 12% in 24 hours. In case of 99m Tc-Nanocis inguinal lymph node was visualized in all animals for 15 min when it was accumulated on the average 1.03% of the administered dose. Plateau of 99m Tc-Nanocis accumulation in the lymph node (average 2.05%) occurred after 2 hours of the study and remained almost on the same level (in average 2.3%) for 24 hours. Thus, the experimental study of a new domestic radiopharmaceutical showed that the 99m Tc-Al 2 O 3 accumulates actively in the lymph nodes several times as compared to the imported analogue and its practical application will facilitate intraoperative identification of sentinel lymph nodes.

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