Effect of substituents on the UV spectra of supermolecular system: Silver nanoparticles with bi‐aryl Schiff bases containing hydroxyl

Abstract

Effect of substituents on the ultraviolet (UV) spectra of supermolecular system involving silver nanoparticles (AgNPs) and Schiff bases was investigated. AgNPs and 49 samples of model compounds (MC), bi-aryl Schiff bases containing hydroxyl (XBAY, involving 4-OHArCH¼NArY, 2-OHArCH¼NArY, XArCH¼NAr-4′-OH, and XArCH¼NAr-2′-OH), were synthesized. The size of AgNPs was characterized by transmission electron microscopy (TEM), and the UV absorption spectra of AgNPs, XBAYs, and MC-AgNPs mixed solutions were measured, respectively. The results show that (1) the size of AgNPs is larger in MC-AgNPs solutions than that in AgNPs solution due to the distribution of MC molecules on the surface of AgNPs; (2) the UV absorption wavelength of XBAYs changes in the action of AgNPs and their wavelength shift exists limitation between XBAY and MC-AgNPs solutions; and (3) the wavelength shift limit of MC-AgNPs (λ WSL ) is influenced by the substituents X and Y and the position of hydroxyl OH. The wavenumber Δν WSL of λ WSL can be quantified by employing the excited-state substituent constant σ ex CC and Hammett constant σ of substituents X and Y. Comparing with the 4-OH, the 4′-OH makes the Δν WSL a red shift, whereas the 2′-OH, comparing with the 2-OH, makes the Δν WSL a blue shift.

Investigation on the UV spectra of the supermolecular system involving silver nanoparticles–substituted N‐(phenyl‐ethylene)‐anilines

“…In Cao et al's report, [25] the investigated compounds have a bridging bond CH═N, whereas the 2-OH-XPEAY of this work have the bridging bond C(Me)═N with a side group (Me). Compared with the results reported by Cao et al, [25] is there any difference about the influence of group X and Y on the λ′ max,lim in AgNPs-(II) solutions. We will discuss the above topics in following section.…”

“…We want to know how do the groups X and Y affect the λ′ max,lim in AgNPs-(I) and AgNPs-(II) solutions. We noticed that Cao et al [25] recently reported the effect of substituents on the UV spectra of supermolecular system involving AgNPs with bi-aryl Schiff bases (2-OHArCH═NArY and XArCH═NArOH-2′). In Cao et al's report, [25] the investigated compounds have a bridging bond CH═N, whereas the 2-OH-XPEAY of this work have the bridging bond C(Me)═N with a side group (Me).…”

“…We noticed that Cao et al [25] recently reported the effect of substituents on the UV spectra of supermolecular system involving AgNPs with bi-aryl Schiff bases (2-OHArCH═NArY and XArCH═NArOH-2′). In Cao et al's report, [25] the investigated compounds have a bridging bond CH═N, whereas the 2-OH-XPEAY of this work have the bridging bond C(Me)═N with a side group (Me). Compared with the results reported by Cao et al, [25] is there any difference about the influence of group X and Y on the λ′ max,lim in AgNPs-(II) solutions.…”

“…AgNPs were synthesized according to the literatures. [25,26] In which, the fsDNA (9.6 mL, 1.0 g L −1 ), AgNO 3 (0.4 mL, 20.0 mM), and NaBH 4 (1.0 mL, 2.0 mM) solutions were used (total volume 11 mL). In the prepared AgNPs solution, the final concentration of Ag is c Ag = 0.727 mM.…”

“…These Δν WSL values all were listed in Table 1. Cao et al [25] proposed a six-parameter expression (1) to quantify the Δν WSL of AgNPs with biaryl Schiff bases containing hydroxyl (2/2′-OH) (expressed with XBAY) system. The meanings of variables in Equation (1) are as follows: The σ and σ ex CC are Hammett electronic effect constant and the excited-state substituent constant of group X or Y in XBAY molecule, respectively.…”