Structure, Conformation, and Dynamics of P,N-Containing Cyclophanes in Solution

Abstract

3D structures in solution of highly symmetrical N,P-containing macrocycles were established by a variety of 2D NMR correlation techniques. It was shown that a number of magnetically equivalent fragments in such symmetrical systems can be estimated by NMR diffusion measurement. The title compounds adopt a helical conformation of the macrocycles in solution. The extent of twisting and the size of the intramolecular cavity are determined by steric hindrance of the aromatic substituents on the exocyclic phosphorus atoms with phenylene and dimethylmethylene groups forming the macrocycle. In solution these macrocycles host aromatic guests inside the cavity.

Deoxygenation of Some α-Dicarbonyl Compounds by Tris(diethylamino)phosphine in the Presence of Fullerene C60

“…For example, for 13 the NOE between N-CH 3 and H 7 allows a direct assignment of all protons in the "benzo" fragment. HMBC correlations between the CH 3 protons and the CdO (C 2 , 169.09 ppm) and between the H4 and sp 3 carbon An almost perfect correlation of the calculated (GIAO B3LYP/ 6-31G(d)//HF/6-31G) [45][46][47][48] versus experimental 13 C chemical shifts (R 2 = 0.998, see the Supporting Information) provides additional support for the validity of the above conclusion about the structure. The same is also true for compounds 14-16.…”

Cyclic aminomethylphosphines as ligands: Balancing between rational design and unpredicted findings

“…10 Unexpectedly an effective strategy of P,N-containing macrocycles design was developed based on covalent self-assembly processes in the course of Mannich-type condensations in threecomponent systems: primary phosphine (or secondary diphosphine) --formaldehyde --diamine with spatially divided functional groups (or primary amine). 11 This approach (Scheme 2) allowed to obtaine various types of macrocyclic phosphines, namely cage cyclophanes with 1,5-diaza-3,7-diphosphacyclooctane fragment in the basic framework, [12][13][14][15] cyclophanes with linear P,Ncontaining spacers, 11 P,N-containing corands 11, 16-18 and the first P,N-containing cryptand 19,20 with four phosphine centers. 5 However novel ligands showed unpredicted properties like unique reversible slitting of macrocycles on to the smaller cycles, 18 rapid interconversion of isomers catalyzed by both acids and transitional metals, 21 bridging behavior of usually chelating ligands and an unexpectedly high influence of dangling substituents on N-atoms on to the catalytic and luminescent properties of P-complexes.…”

Determination of the Methylpheophorbide а Association Degree by Diffusion Ordered NMR Spectroscopy (DOSY)

“…[4][5][6][7] It is known that DOSY method can be used for study of the molecules association in a solution, this method allows to fix the formation of molecular associates with relatively strong hydrogen bonds or ionic interactions between molecules. [8][9][10] Determination of the Methylpheophorbide а Association Degree by DOSY DOSY method was also used for multiporphyrin systems molecular weights estimation, but the porphyrin macrocycles in the objects of these investigations are connected with involvement of covalent bonds, [11] or through strong coordination interactions, [12][13][14][15][16][17] or hydrogen bonds. [18] The porphyrin associates with weaker intermolecular interactions have not been investigated by this method.…”