23Review

J. Jpn. Soc. Colour Mater., 90〔1〕，23–26（2017）

Overview of Synthetic Methodologies for Development of Cationic Gemini Surfactants
Avinash Bhadani＊,†, Sukhprit Singh＊＊, Raman K amboj＊＊＊ and Vinay Chauhan＊＊＊＊＊ Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan＊＊ Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India＊＊＊ Department of Chemistry, D.A.V College, Sector 10, Chandigarh, India＊＊＊＊ Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden†Corresponding Author, E-mail: abhadani@rs.tus.ac.jp(Received August 25, 2016; Accepted October 3, 2016)

Abstract
In the present article we have summarized our research work related to synthesis and investigation of several new types of cationic gemini
surfactants containing different headgroups (i.e. pyridinium, imidazolium, pyrrolidinium, piperidinium, morpholinium). We have used threedifferent principal methodologies to develop several new types of gemini surfactants: (1) regioselective co-bromination protocol followed byquaternization (2) regioselective epoxy ring opening reactions followed by quaternization (3) Alkylation reactions followed by quaternization.
These cationic surfactants have been investigated for their surface and physicochemical properties and the studies have established thesesurfactants to be superior compared to conventional/commercially available cationic surfactants.
Key-words: Gemini surfactant, Synthesis, CMC, Surface properties, DNA interaction, Cytotoxicity

1．Introduction
Cationic surfactants are important category of surfactant
molecules, which are important constituent of several
commercial formulations. Gemini cationic surfactantsconsisting of two positively charged hydrophilic headgroupand two hydrophobic tail often connected by a spacer are
considered superior surfactants molecules due to their affinity
to self-aggregate at much lower concentration in aqueous
solution compared to the monomeric counterparts 1,2 ) .
In recent years several new types of the cationic gemini
surfactants have been developed and investigated fordifferent application areas. These gemini surfactants havedemonstrated ability to interact and condense DNA, form
complexes with active drug molecules and enhanced ability tokill and retard the growth of pathogenic microorganisms, andhence are presently being investigated for several biomedical
applications. These surfactants often self-aggregate for form
micelles at very low concentration and demonstrate superior
surfactant properties compared to conventional monomeric[Name] BHADANI Avinash[ Current Position ] Assistant Professor at ResearchInstitute of Science & Technology, Tokyo
University of Science, 2641 Yamazaki, Noda,
Chiba.
[Hobbies] Traveling, visiting new places and photography.
[ Experience ] Completed Ph.D. degree from Guru
Nanak Dev University in 2012 . Worked as
Postdoctoral Researcher at City College of
New York, New York ( 2012 - 2013 ) and at
Tokyo University of Science ( 2013-2015 ).

surfactants. Currently these surfactant molecules are being
considered for several emerging application areas. They areable to act as soft template for synthesis of mesoporous/
microporous and are being used to develop several newtypes of hollow inorganic materials. These surfactants arealso able to stabilize several metal-based nanoparticles3).
The versatile physicochemical properties and wide rangeof application ranging from biomedical to material science
led to development of several new types of cationic gemini
surfactants.

2．Experimental methodology
for synthesis of gemini surfactants
We in our research group have adopted three principal
methodologies for the synthesis of new types of gemini
surfactants.
2.1 Regioselective co-bromination protocol followed byquaternization
One of the principal methodology used for the synthesis of
new type of gemini surfactants containing thioether spacer
units is regioselective electrophilic co-bromination using
N-bromosuccinimide (NBS) as organic reagent (Fig. 1a).
NBS forms a cyclic bromonium ion with terminal alkenes at
low temperature. Dithiols, which are strong nucleophiles, areable to selectively attack the less-hindered terminal carbon
in a regioselective manner via anti-Markovnikov addition toform reactive intermediates, which can be quaternized withpyridine or N-methylimidazole to get new type of thioether
spacer containing gemini surfactants4-6).

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