Structural and Optical Properties of Struvite. Elucidating Structure of Infrared Spectrum in High Frequency Range.

Dominik Sidorczuk,Bartolomeo Civalleri,Katarzyna Pernal,Jolanta Prywer,Marcin Kozanecki

doi:10.1021/acs.jpca.0c04707

Dominik Sidorczuk, Bartolomeo Civalleri + Show 3 more

Open Access

https://doi.org/10.1021/acs.jpca.0c04707

Copy DOI

Abstract

Study of structure and optical properties of magnesium ammonium phosphate hexahydrate crystal known as struvite is presented. Experimentally determined infrared (IR) and ultraviolet–visible (UV–vis) spectra are compared with the theoretical predictions of density functional methods. Examination of the interatomic bond lengths, Mulliken atomic charges, and binding energies of water in the magnesium hexahydrate cation, together with the analysis of the hydrogen bond pattern have allowed us to explain a special feature of the IR spectrum of struvite, a blueshift of the band corresponding to the O–H stretching mode. This mode has been assigned to a “dangling” hydroxyl group in one of the water molecules in magnesium hexahydrate. Using experimentally obtained UV–vis spectrum and performing Tauc plots analysis, optical bandgap of struvite has been narrowed to a range from 5.92 to 6.06 eV.

Highlights

Magnesium ammonium phosphate hexahydrate, MgNH4PO4· 6H2O, known as struvite, has been widely investigated over the past decade for several reasons
The M05-2X functional has led to obtaining bond lengths differing from the experimental values on average by only 0.009 Å
It has been revealed that one water molecule has a dangling OH bond, a consequence of the fact that the related H atom is not connected via hydrogen bonds (H-bonds) with the environment

Summary

Introduction

MgNH4PO4· 6H2O, known as struvite, has been widely investigated over the past decade for several reasons. The main reason for which physicochemical properties of struvite are examined results from the fact that it constitutes the main component of the so-called infectious urinary stones representing up to 30% of all urinary stones.[8] Studies show that in highly developed countries, the incidence of infectious urolithiasis is steadily increasing, indicating that infectious urinary stones are a social problem. The infection is the result of the activity of microorganisms producing urease, mainly from Proteus species.[9] Struvite stones may grow rapidly over a period of weeks to months and, if not adequately treated, can develop into a large stone that fills the entire intrarenal collecting system. Patients with infectious stones who receive no treatment have about a 50% chance of losing a kidney.[10]

Objectives

Methods

Findings

Conclusion