The Metal Effect on Self-Assembling of Oxalamide Gelators Explored by Mass Spectrometry and DFT Calculations

Dabić, Dario; Brkljačić, Lidija; Žinić, Mladen; Vianello, Robert; Frkanec, Leo; Kobetić, Renata (2018) The Metal Effect on Self-Assembling of Oxalamide Gelators Explored by Mass Spectrometry and DFT Calculations. Journal of The American Society for Mass Spectrometry, 28 (1). pp. 103-113. ISSN 1044-0305

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Abstract

Gels formed by self-assembly of small organic molecules are of wide interest as dynamic soft materials with numerous possible applications, especially in terms of nanotechnology for functional responsive biomaterials, biosensors, and nanowires. Four bis-oxalamides were chosen to show if electrospray ionization mass spectrometry (ESI-MS) could be used as a prediction of a good gelator and also to shed light on the gelation processes. By inspecting the gelation of several solvent, we showed that bis(amino acid)oxalamide 1 proved to be the most efficient, also being able of forming the largest observable assemblies in the gas phase. The formation of single charged assemblies holding from one up to six monomer units is the outcome of the strong intermolecular H-bonds, particularly among terminal carboxyl groups. The variation of solvents from polar aprotic towards polar protic did not have any significant effects on the size of the assemblies. The addition of a salt such as NaOAc or Mg(OAc)2, depending on the concentration, altered the assembling. Computational analysis at the DFT level aided in the interpretation of the observed trends and revealed that individual gelator molecules spontaneously assemble to higher aggregates, but the presence of the Na+ cation disrupts any gelator organization since it becomes significantly more favorable for gelator molecules to bind Na+ cations up to the 3:1 ratio than to self-assemble, being fully in line with experimental observations reported here.

Item Type:	Article
Additional Information:	The authors gratefully acknowledge Dr. J. Makarevic, (Laboratory for Supramolecular Chemistry, Division of Organic Chemistry and Biochemistry, Ruder Boskovic Institute, Zagreb, Croatia) for aid in the synthesis of gelators and the preparation of gels samples. This work was supported by the Ministry of Science, Education, and Sports of the Republic of Croatia under grant number 098-0982914-2935. R.V. gratefully acknowledges the financial support from the Croatian Science Foundation (HRZZ) under grant number IP-2014-09-3386 and L.F. under grant number IP-11-2013-7387.
Uncontrolled Keywords:	Oxalamide gelators; Self-assembly; ESI–MS, DFT
Subjects:	NATURAL SCIENCES > Chemistry NATURAL SCIENCES > Chemistry > Organic Chemistry
Divisions:	Division of Organic Chemistry and Biochemistry
Projects:	Project title Project leader Project code Project type Sinteza novih biološki aktivnih derivata nukleobaza i nukleotida- Biserka Žinić 098-0982914-2935 MZOS Supramolekulska sinteza samo-organizirajućih funkcionalnih nanomaterijala i kompleksnih kemijskih sustava-SInFONIA Leo Frkanec IP-2013-11-7387 HRZZ Dizajn i sinteza novih dušikovih heterocikličkih fluorofora i fluorescentnih nanomaterijala kao kemijskih senzora za pH i metalne ione-iNFiNiTE–SENS Robert Vianello IP-2014-09-3386 HRZZ
Depositing User:	Renata Kobetić
Date Deposited:	03 Dec 2019 13:02
URI:	http://fulir.irb.hr/id/eprint/5183
DOI:	10.1007/s13361-017-1834-5

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