Diverse Structural Ag(I) Supramolecular Complexes Constructed from Multidentate Dicyanoisophorone-Based Ligands: Structures and Enhanced Luminescence

Abstract

Two multidentate ligands containing a delocalized π-electron system, 2-{5,5-dimethyl-3-[2-(pyridin-3-yl)-ethenyl]­cyclohex-2-enylidene}­propanedinitrile (L1) and 2-{5,5-dimethyl-3-[2-(pyridin-2-yl)-ethenyl]­cyclohex-2-enylidene}­propanedinitrile (L2), were synthesized. By self-assembly of the ligands with silver­(I) salts, six supramolecular complexes, [Ag­(L1)­(TsO)­(H2O)]2 (1), {[Ag3(L1)2(H2O)]­(ClO4)3} n (2), {[Ag­(L1)­(NO3)]·0.5C6H6} n (3), {[Ag­(L2)­(NO3)]·0.5C6H6} n (4), [Ag­(L2)2]­(ClO4) (5), and [Ag­(L2)2]­(PF6) (6), with different structures and topologies were obtained. In polymer 2, L1 acts as a tridentate ligand to bind Ag­(I) ions to form a one-dimensional (1D) supramolecular structure. However, when the ligands adopt bidentate coordination modes to coordinate with Ag­(I) ions through the pyridyl nitrogen atom and one cyano nitrogen atom, the dinuclear supramolecular complex 1, 1D coordination polymer 3, and two-dimensional (2D) coordination polymer 4 were obtained. In 5 or 6, only the pyridyl nitrogen atom of L2 ligand coordinates with the Ag­(I) ion to form a mononuclear complex. The multiple coordination modes of the multidentate ligands and the effect of anions and solvents play important roles in the structural and topological diversity. The luminescent properties were investigated. Compared with the ligands, the complexes show superior luminescent properties with red-shifted and enhanced emission as well as longer fluorescence lifetimes, which indicates that they may be good candidates for optical materials.

Comparative Study of Structures and Luminescent Properties of Three Ag(I) Complexes Utilizing an Achiral Bipyridyl-N or Its Axially Chiral N-Oxide Analogue

“…59 Meanwhile, compared to the free H 2 L N , the enhanced luminescence intensity of 1 is mostly due to the coordination of Ag(I) to H 2 L N and argentophilic interactions, effectively resulting in the increasing conformational rigidity of L N 2− and inhibition of the radiationless decay process. 30,40,42 However, the luminescent intensities of 2 and 3 become weaker in contrast with (R,S)-H 2 L NO and 1, which is much different from the previously reported Eu(III) complexes and Ag(I) complex with N-oxide groups that show more intense luminescent emission than that of bipyridyl-N, 10,11,60 which is perhaps because the weakened conjugacy after coordination. Moreover, the enhanced intensity of 2 compared with 3 is probably due to the increasing amounts of water molecules supporting the luminescence, the rigidity difference of their host frameworks, and the coordination diversity of Ag(I) ions.…”

“…The Ag­(I) ion has received attention for its flexible coordination sphere and argentophilic interactions. − As a soft Lewis acid, it is a good native match for the flexible coordinative tendencies of bipyridyl ligands . However, as we have seen, until now, only one example of a one-dimensional Ag­(I) complex with H 2 L N has been reported, but its N -oxide Ag­(I) complex still does not exist.…”

Crystal Structures and Spectroscopic Properties of Metal–Organic Frameworks Based on Rigid Ligands with Flexible Functional Groups

“…The emission decay lifetimes of 1 , 2 , 4 and L1 ligand are as follows: L1 ligand, τ 1 = 9.71 μs (50.88%), τ 2 = 1.30 μs (49.12%) (χ 2 = 1.141); complex 1 , τ 1 = 9.85 μs (49.91%), τ 2 = 1.24 μs (50.09%) (χ 2 = 1.075); complex 2 , τ 1 = 10.62 μs (48.11%), τ 2 = 1.30 μs (51.89%) (χ 2 = 1.133); complex 4 , τ 1 = 9.43 μs (54.97%), τ 2 = 1.13 μs (45.03%) (χ 2 = 1.105). As we know, emission lifetime value of many metal–organic frameworks is nanosecond, the lifetime of complexes 1 , 2 , and 4 is longer than this value. Complexes with the life span at the microsecond level are classified as phosphorescent materials.…”

Doping potassium ions in silver cyanide complexes for green luminescence

“…calcd for 2 (%), C 2 H 2 AgKN 2 O: C, 11.07;H,0.93;N,12.91. Found: C,11.15;H,1.02;N,12.89. FT-IR (KBr, cm −1 ): 3433(br, m), 2983(w), 2523(w), 2133(s), 1631(m), 1479(m), 1434(w), 1388(m), 1364(w), 1170(m), 1053(w), 996(m), 784(m).…”