Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor

This paper describes the synthesis and characterization of seven different copper(II) coordination compounds, as well as the formation of a protonated ligand involving all compounds from the same reaction. Their synthesis required hydrothermal conditions, causing the partial in situ transformation o...

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Main Authors: Verónica G. Vegas, Andrea García-Hernán, Fernando Aguilar-Galindo, Josefina Perles, Pilar Amo-Ochoa
Format: Article
Language:English
Published: MDPI AG 2023-06-01
Series:Polymers
Subjects:
Online Access:https://www.mdpi.com/2073-4360/15/13/2827
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author Verónica G. Vegas
Andrea García-Hernán
Fernando Aguilar-Galindo
Josefina Perles
Pilar Amo-Ochoa
author_facet Verónica G. Vegas
Andrea García-Hernán
Fernando Aguilar-Galindo
Josefina Perles
Pilar Amo-Ochoa
author_sort Verónica G. Vegas
collection DOAJ
description This paper describes the synthesis and characterization of seven different copper(II) coordination compounds, as well as the formation of a protonated ligand involving all compounds from the same reaction. Their synthesis required hydrothermal conditions, causing the partial in situ transformation of 5-fluoro uracil-1-acetic acid (5-FUA) into an oxalate ion (ox), as well as the protonation of the 4,4′-bipyridine (bipy) ligand through a catalytic process resulting from the presence of Cu(II) within the reaction. These initial conditions allowed obtaining the new coordination compounds <b>[Cu<sub>2</sub>(5-FUA)<sub>2</sub>(ox)(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP2)</b>, <b>[Cu(5-FUA)<sub>2</sub>(H<sub>2</sub>O)(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP3)</b>, as well as the ionic pair <b>[(H<sub>2</sub>bipy)<sup>+2</sup> 2NO<sub>3</sub><sup>−</sup>] (1)</b>. The mother liquor evolved rapidly at room temperature and atmospheric pressure, due to the change in concentration of the initial reagents and the presence of the new chemical species generated in the reaction process, yielding CPs <b>[Cu(5-FUA)<sub>2</sub>(bipy)]<sub>n</sub>·3.5n H<sub>2</sub>O</b>, <b>[Cu<sub>3</sub>(ox)<sub>3</sub>(bipy)<sub>4</sub>]<sub>n</sub></b> and <b>[Cu(ox)(bipy)]<sub>n</sub></b>. The molecular compound <b>[Cu(5-FUA)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O</b> (more thermodynamically stable) ended up in the mother liquor after filtration at longer reaction times at 25 °C and 1 atm., cohabiting in the medium with the other crystalline solids in different proportions. In addition, the evaporation of H<sub>2</sub>O caused the single-crystal to single-crystal transformation (SCSC) of <b>[Cu(5-FUA)<sub>2</sub>(H<sub>2</sub>O)(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP3)</b> into <b>[Cu(5-FUA)<sub>2</sub>(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP4)</b>. A theoretical study was performed to analyze the thermodynamic stability of the phases. The observed SCSC transformation also involved a perceptible color change, highlighting this compound as a possible water sensor.
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spelling doaj.art-dba98aa8f1c24952a0b644597e2109e52023-11-18T17:20:40ZengMDPI AGPolymers2073-43602023-06-011513282710.3390/polym15132827Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity SensorVerónica G. Vegas0Andrea García-Hernán1Fernando Aguilar-Galindo2Josefina Perles3Pilar Amo-Ochoa4Departamento de Química Inorgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, SpainDepartamento de Química Inorgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, SpainDepartamento de Química, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, SpainLaboratorio de DRX Monocristal, Servicio Interdepartamental de Investigación, Universidad Autónoma de Madrid, 28049 Madrid, SpainDepartamento de Química Inorgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, SpainThis paper describes the synthesis and characterization of seven different copper(II) coordination compounds, as well as the formation of a protonated ligand involving all compounds from the same reaction. Their synthesis required hydrothermal conditions, causing the partial in situ transformation of 5-fluoro uracil-1-acetic acid (5-FUA) into an oxalate ion (ox), as well as the protonation of the 4,4′-bipyridine (bipy) ligand through a catalytic process resulting from the presence of Cu(II) within the reaction. These initial conditions allowed obtaining the new coordination compounds <b>[Cu<sub>2</sub>(5-FUA)<sub>2</sub>(ox)(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP2)</b>, <b>[Cu(5-FUA)<sub>2</sub>(H<sub>2</sub>O)(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP3)</b>, as well as the ionic pair <b>[(H<sub>2</sub>bipy)<sup>+2</sup> 2NO<sub>3</sub><sup>−</sup>] (1)</b>. The mother liquor evolved rapidly at room temperature and atmospheric pressure, due to the change in concentration of the initial reagents and the presence of the new chemical species generated in the reaction process, yielding CPs <b>[Cu(5-FUA)<sub>2</sub>(bipy)]<sub>n</sub>·3.5n H<sub>2</sub>O</b>, <b>[Cu<sub>3</sub>(ox)<sub>3</sub>(bipy)<sub>4</sub>]<sub>n</sub></b> and <b>[Cu(ox)(bipy)]<sub>n</sub></b>. The molecular compound <b>[Cu(5-FUA)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O</b> (more thermodynamically stable) ended up in the mother liquor after filtration at longer reaction times at 25 °C and 1 atm., cohabiting in the medium with the other crystalline solids in different proportions. In addition, the evaporation of H<sub>2</sub>O caused the single-crystal to single-crystal transformation (SCSC) of <b>[Cu(5-FUA)<sub>2</sub>(H<sub>2</sub>O)(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP3)</b> into <b>[Cu(5-FUA)<sub>2</sub>(bipy)]<sub>n</sub>·2n H<sub>2</sub>O (CP4)</b>. A theoretical study was performed to analyze the thermodynamic stability of the phases. The observed SCSC transformation also involved a perceptible color change, highlighting this compound as a possible water sensor.https://www.mdpi.com/2073-4360/15/13/2827copperhumidity sensorscoordination compoundscoordination polymerstheoretical calculations
spellingShingle Verónica G. Vegas
Andrea García-Hernán
Fernando Aguilar-Galindo
Josefina Perles
Pilar Amo-Ochoa
Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor
Polymers
copper
humidity sensors
coordination compounds
coordination polymers
theoretical calculations
title Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor
title_full Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor
title_fullStr Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor
title_full_unstemmed Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor
title_short Structural and Theoretical Study of Copper(II)-5-fluoro Uracil Acetate Coordination Compounds: Single-Crystal to Single-Crystal Transformation as Possible Humidity Sensor
title_sort structural and theoretical study of copper ii 5 fluoro uracil acetate coordination compounds single crystal to single crystal transformation as possible humidity sensor
topic copper
humidity sensors
coordination compounds
coordination polymers
theoretical calculations
url https://www.mdpi.com/2073-4360/15/13/2827
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