Synthesis and characterization of pH responsive D-glucosamine based molecular gelators.

Navneet Goyal,Sonu Shrestha,Guijun Wang,Hari P R Mangunuru,Bargav Parikh

doi:10.3762/bjoc.10.328

Abstract

Small molecular gelators are a class of compounds with potential applications for soft biomaterials. Low molecular weight hydrogelators are especially useful for exploring biomedical applications. Previously, we found that 4,6-O-benzylidene acetal protected D-glucose and D-glucosamine are well-suited as building blocks for the construction of low molecular weight gelators. To better understand the scope of D-glucosamine derivatives as gelators, we synthesized and screened a novel class of N-acetylglucosamine derivatives with a p-methoxybenzylidene acetal protective group. This modification did not exert a negative influence on the gelation. On the contrary, it actually enhanced the gelation tendency for many derivatives. The introduction of the additional methoxy group on the phenyl ring led to low molecular weight gelators with a higher pH responsiveness. The resulting gels were stable at neutral pH values but degraded in an acidic environment. The release profiles of naproxen from the pH responsive gels were also analyzed under acidic and neutral conditions. Our findings are useful for the design of novel triggered release self-assembling systems and can provide an insight into the influence of the the structure on gelation.

Highlights

Low molecular weight gelators (LMWGs) have drawn great attention over the past few decades due to the formation of supramolecular structures and their potential applications as advanced materials [1-7]
We have studied the selective functionalization of monosaccharides, such as glucose and glucosamine, and obtained effective low molecular weight gelators for both organic solvents and aqueous mixtures [35-40]
The stability of the DMSO/H2O gels upon the addition of water for compounds 16, 17, 20 and 21 was tested, and the gels were almost the same after 20 h (Figure S2 in Supporting Information File 1). These results indicate that the gels are stable under neutral conditions and can rapidly dissolve in an acidic environment

Summary

Introduction

Low molecular weight gelators (LMWGs) have drawn great attention over the past few decades due to the formation of supramolecular structures and their potential applications as advanced materials [1-7]. We have studied the selective functionalization of monosaccharides, such as glucose and glucosamine, and obtained effective low molecular weight gelators for both organic solvents and aqueous mixtures [35-40]. The p-methoxybenzylidene acetal can be cleaved in the presence of acids much more readily which results in pH responsive triggered release organogel or hydrogels, provided that the derivatives of compound 3 are effective gelators.

Results

Conclusion