Synthesis, Crystal Structures and Lithium Encapsulation by Some Phenolic Aza Cages

✍ Scribed by Mauro Micheloni; Mauro Formica; Vieri Fusi; Paolo Romani; Roberto Pontellini; Paolo Dapporto; Paola Paoli; Patrizia Rossi; Barbara Valtancoli

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 309 KB
• Volume: 2000
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/(sici)1099-0682(200001)2000:1<51::aid-ejic51>3.0.co;2-r

✦ Synopsis

Three new macrocyclic cages 1, 2 and 3, able to selectively occurs. UV/Vis studies in aqueous solution show a significant shift towards high energy of the λ max in the lithium complex, encapsulate the lithium ion, were studied. The synthesis and characterization of 2 and 3 are reported. The basicity indicating the potential for application of these ligands in colourimetric analysis. The crystal structure of 1 was behaviour of the three cages was investigated by spectrophotometry and by 1 H and 13 C NMR spectroscopy. examined by single crystal X-ray diffraction. Data collection was performed on two samples, namely 1a and 1b, obtained The protonation constants were determined by potentiometric methods in aqueous solution (I = 0.15 mol dm - from two different crystallization procedures. Crystals of 1a are monoclinic, space group P2 1 /n, while 1b crystallized in 3 NMe 4 Cl, T = 298 ± 0.1 K) and were found to be logK 1 = 11.67(5), 10.77(7), 11.17(7); logK 2 = 7.76(5), 5.7(1), 5.6(1); an orthorhombic space group Pc2 1 b. The cell parameters are a = 12.423( 3), b = 14.378( 9), c = 28.436(7) A ˚, β = 93.74(2)°for logK 3 = 1.3(1), 2.4(1), 1.9(1) for 1, 2, and 3, respectively. The lithium equilibrium complex formation Li + + L = LiL H-1 + H + 1a, and a = 10.674(4), b = 14.408(2), c = 17.034(2) A ˚for 1b.

Molecular simulations were carried out on both was monitored by 13 C and 7 Li NMR spectroscopy, as well as by spectrophotometric and potentiometric techniques; log conformational isomers 1a and 1b, with results indicating that the two isomers have essentially the same flexibility. values of -9.1(1) and -8.0(1) were found for 1 and 3, respectively. For 2, precipitation of the lithium complex azo chromophores external to the molecular cavity have

Equilibrium Studies