A dual perspective on the microwave-assisted synthesis of HCN polymers towards the chemical evolution and design of functional materials

José L De La Fuente,Marta Ruiz-Bermejo,Cristina Pérez-Fernández,Lucía Hortal,Pilar Valles,Eva Mateo-Martí

doi:10.1038/s41598-020-79112-5

José L De La Fuente, Marta Ruiz-Bermejo + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-79112-5

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Abstract

In this paper, the first study on NH4CN polymerization induced by microwave radiation is described, where a singular kinetic behaviour, especially when this reaction is conducted in the absence of air, is found. As a result, a complex conjugated N-heterocyclic polymer system is obtained, whose properties are very different, and even improved according to morphological features, characterized by their X-ray diffraction patterns and scanning electron microscopy analysis, with respect to those produced under conventional thermal treatment. In addition, a wide variety of relevant bioorganics have been identified, such as amino acids, nucleobases, co-factors, etc., from the synthetized NH4CN polymers. These particular families of polymers are of high interest in the fields of astrobiology and prebiotic chemistry and, more recently, in the development of smart multifunctional materials. From an astrobiological perspective, microwave-driven syntheses may simulate hydrothermal environments, which are considered ideal niches for increasing organic molecular complexity, and eventually as scenarios for an origin of life. From an industrial point of view and for potential applications, a microwave irradiation process leads to a notable decrease in the reaction times, and tune the properties of these new series macromolecular systems. The characteristics found for these materials encourage the development of further systematic research on this alternative HCN polymerization.

Highlights

In this paper, the first study on NH4CN polymerization induced by microwave radiation is described, where a singular kinetic behaviour, especially when this reaction is conducted in the absence of air, is found
A second section focuses on the study of soluble fractions, and a part closer to analytical chemistry attempts to identify all the molecular species that can be generated from both reaction products after a hydrolytic process
The pressure parameter is directly related to the temperature in the microwave-assisted polymerizations, and high pressures seem to produce more ordered and crystalline NH4CN polymers than those synthetized under atmospheric pressure

Summary

Introduction

The first study on NH4CN polymerization induced by microwave radiation is described, where a singular kinetic behaviour, especially when this reaction is conducted in the absence of air, is found. HCN polymers are a heterogeneous family of very complex organic substances synthesized from net HCN, soluble salts of cyanide (NaCN, KCN or N H4CN), aminomalononitrile, diaminomaleonitrile (AMN, DAMN, the formal trimer and tetramer of HCN, respectively), or formamide under a wide range of experimental conditions They are of great interest in studies about the origin of life and in the fields of prebiotic chemistry and astrobiology, since the first prebiotic synthesis of adenine by Oró in the early 1 960s1. The aqueous soluble oligomeric/polymeric phase (sol fraction) was examined by UV–vis spectroscopic measurements and GC–MS and later concentrated using ultracentrifugation devices All of these results are discussed considering the dual interest of these polymerizations in prebiotic chemistry as well as in materials science, providing new insights in both fields and encouraging the development of systematic research on microwave-initiated HCN polymerization

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