Complexes of lanthanoid salts with macrocyclic ligands. 34. Glasslike structure in crystalline macrocyclic complexes: synthesis, x-ray diffraction, and laser-spectroscopic investigation of neodymium(III) and europium(III) complexes with 4,13-dimethyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane