Characterization of Chain Molecular Assemblies in Long-Chain, Lamellar Copper Alkylsulfonates:  Self-Assembled Monolayer vs Bilayer Structure

Abstract

Direct characterization of chain molecular structures in a series of layered organic/inorganic longchain alkylsulfonates, Cu(C n H 2n+1 SO 3 ) 2 ‚yH 2 O (CuSO 3 -n, where n)10, 12 and y ) 4 for group I; n ) 14, 16, 18 and y ) 2 for group II), using combined application of Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (XRD) is reported. These compounds show a layered structure, as determined by XRD, consisting of alternating organic alkylsulfonate layers and inorganic copper(II) hydrate layers, with interlayer distances of up to 3.82 nm. It is worth noting that the layer-to-layer distance can be easily and rationally metered by choosing alkylsulfonates of different lengths: Shorter alkylsulfonates, group I, yield an interdigitated monolayer structure with shorter periodicity, whereas longer alkylsulfonates, group II, yield a noninterdigitated bilayer structure with longer periodicity. The goal was to correlate the structural changes by increasing the chain length, monitored by XRD, with the alkyl chain structure detected by FTIR spectroscopy. From the FTIR spectra, the distinguishable features between the two groups appear in two different wavenumber regions, i.e., the hydrogen-bonding region (2900-3500 cm -1 ) and the sulfonate-stretching region (1000-1250 cm -1 ), indicating that the hydrophilic layers of the two groups are completely different. Furthermore, a detailed investigation of the C-H modes, including the stretching, scissoring, and rocking modes, reveals that the chain-packing modes of the two groups are different, even though the alkyl chains in the CuSO 3 -n series are all in an all-trans conformational state. The change in the monolayer to bilayer packing with the alkyl chain length, arising from the intermolecular interaction between the alkyl chains, is explained by the rearrangement of the alkyl chains from orthorhombic to hexagonal subcells with decreasing packing density.

Thermochromic Meltable Materials with Reverse Spin Transition Controlled by Chemical Design

“…IR spectroscopic data in the region of characteristic CÀH absorption bands reveal the conformation of aliphatic chains and the reason for the different positions of the halo.F or crystalline and melted pm2-6 and melted pm2-8,t he n anti (C À H) = 2925-2928 cm À1 and n sym (CÀH) = 2854-2856 cm À1 suggest significant gauche population of aliphatic chains [14] that corroborates the single crystal data of pm2-6 ( Figure 7; Supporting Information, Figures S12, S13). Form elted pm2-10, pm2-12, pm2-14 the peak maxima at n anti (C À H) = 2920-2922 and n sym (C À H) = 2850-2851 cm À1 suggest that the majority of C À Cb onds are in the trans conformation.…”

“…Form elted pm2-10, pm2-12, pm2-14 the peak maxima at n anti (C À H) = 2920-2922 and n sym (C À H) = 2850-2851 cm À1 suggest that the majority of C À Cb onds are in the trans conformation. [14] Upon melting the position of the n anti (CÀH) and n sym (CÀH) of pm2-10 are reversibly blue-shifted to the typical gauche values (n anti (CÀH) = 2928 and n sym (CÀH) = 2856 cm À1 at 393 K), while the bands of pm2-6 are insensitive to the temperature rise (Supporting Information, Figure S14).…”

Thermochromic Meltable Materials with Reverse Spin Transition Controlled by Chemical Design

“…Forschungsartikel IR spectroscopic data in the region of characteristic CÀH absorption bands reveal the conformation of aliphatic chains and the reason for the different positions of the halo.F or crystalline and melted pm2-6 and melted pm2-8,t he n anti (C À H) = 2925-2928 cm À1 and n sym (CÀH) = 2854-2856 cm À1 suggest significant gauche population of aliphatic chains [14] that corroborates the single crystal data of pm2-6 ( Figure 7; Supporting Information, Figures S12, S13). Form elted pm2-10, pm2-12, pm2-14 the peak maxima at n anti (C À H) = 2920-2922 and n sym (C À H) = 2850-2851 cm À1 suggest that the majority of C À Cb onds are in the trans conformation.…”

Polyethyleneimine as a novel desorbent for anionic organic dyes on layered double hydroxide surface

“…UV-vis spectra of methyl orange before adsorption, after adsorption and after desorption, inset shows the photos of the methyl orange solution before adsorption (left), after adsorption (middle) and after desorption (right). and amino groups of PEI molecule under the present conditions [48]. In contrast, when the pH value of methyl orange-PEI mixture was 8.0, the symmetric stretching vibration of sulfonate group at 1039 cm À1 just had a slight blue-shift of 2 cm À1 (Fig.…”