Diamine Derivatives And Their Cementitious Properties

Low-molecular-mass organic gelators (LMOGs) have attracted widespread attention of chemists and biochemists due to their unique supramolecular structures and potential application in the fabrication of sensors, photochemistry and electrochemistry. A series of LMOGs were synthesized and their gelation abilities, morphologies as well as self-assembly behaviors in gel state were investigated in detail. Furthermore, a rational mechanism of the formation of organogels was proposed on base of our studies. We obtained some creative results, which were outlined as follows:(1) We synthesized several monochain derivatives of ethylenediamine, which showed strongly gelation ability in a number of organic solvents. The gel melting (T_gel) for toluene gel with 15mg/Ml of the homologues 1-6 increases with increasing alkyl chain length from eight to eighteen carbon atoms. For different concentration, the T_gel increases with increasing concentration and then keeps a certain temperature. Scanning electron microscope(SEM)images reveals a number of fibers with the width in the range of 2-5μm, juxtaposed and intertwined by several long slender aggregations to construct 3D network. FT-IR spectrum demonstrated that the hydrogen bonding in gels and solid powder had some similarities and hydrocarbon chain of organogelator molecules adopted all trans-zigzag conformation in organogels. Via contrastive experiments, we also found that enough intermolecular hydrogen bonding was essential in the formation of organogels. The XRD pattern of the gel cast film shows periodical diffraction peaks, indicating that 1-6 indeed assemble into an ordered structure. It was found that the long spacing (Dn) is smaller than twice the corresponding evaluated molecular lengths (Ln), but much larger than the length of one molecule, demonstrating that the gel aggregates consist of a repeating bilayer unit. According to the linear relationship of the long spacing (Dn) and the alkyl length (n), the title angle can be calculated, which is ca. 25°. Based on the results of SEM, FT-IR, and XRD, it can be deduced that the gel aggregates consist of a repeating bilayer unit, which adopts the head-to-head packing model with highly tilted alkyl chains relative to the bilayer normal. Within the bilayer unit, the compounds are connected by inter-layer hydrogen bonding to form a 3D network and then develop the superstructure. The title angle of the repeating bilayer unit is ca. 25°.(2) The monochain butanediamine derivatives 1-6, the monochain hexanediamine derivatives 7-12 and the monochain octanediamine derivatives 13-18 were synthesized. These three monochain derivatives showed strong gelation ability in a number of organic solvents. The gel melting (T_gel) increases with increasing alkyl chain length from eight to eighteen carbon atoms and then decreases. For different concentration, the T_gel increases with increasing concentration and then keeps a certain temperature. The results of SEM, FT-IR, XRD studies are similar to those of the monochain ethylenediamine derivatives. In the XRD studies, The title angles of the repeating bilayer unit for these three derivatives are ca. 48°, 48°, 41°.(3) From these observations and analyses for the monochain ethylenediamine derivatives, the monochain butanediamine derivatives, the monochain hexanediamine derivatives and the monochain octanediamine, it can be concluded as follows: gelling ability strongly depends on the diamine group; the hydrophile-lypophile balance is a significant factor for gelation; the formation of the bilayer aggregates plays an important role in gel-forming.