Bispidine derivatives L1-L8 were designed for being compatible with coordinative polymerization, synthesized and fully characterized. At variance with more common bispidine ligands, they possess two pyridine moieties with their N-atoms oriented in a divergent fashion and they differ from one another for the group in the N7 position of the scaffold. In-depth structural study of L1-L7 by means of X-ray diffraction on single crystals (SC) provided information as to their packing interactions and their structural modifications when involved in coordination interactions. L1-L8 were then reacted with Mn(II) ions in the presence of different solvents through slow and fast crystallization methods to build novel coordination polymers (CPs) which were characterized through single crystal (SC-XRD) and powder X-ray diffraction (P-XRD) techniques. Extensive structural analysis of CPs, namely 1·TCMSC, 1·NBSC, 2·TCMSC, 4·TCMSC, 4·NBSC, 5·TCMSC, 5·TCM·NBSC was performed, showing in all cases non-interpenetrated 1D ribbon chains, which interacted with each other through ribbon-ribbon packing interactions, according to the ligand’s identity and the trapped solvents. In general, these CPs are assembled via weak inter-ribbon interactions among very robust 1D chains that can arrange one with respect to the others in several orientations, forming channeled as well as non-porous structures. These materials showed a remarkable dynamic behavior as they can undergo solid/liquid and solid/gas guest-exchange processes where ribbon chains are subjected to significant structural re-organization by releasing trapped solvent molecules and accommodating new ones. Notably, such dynamic behavior is dependent on the ligand employed and this was attributed to the extent of inter-ribbon interactions present in the CP which varies due to the presence of different N7 substituents. In this thesis, we present a detailed analysis of the structural features of these novel CPs aiming to determine a structure-property relationship based on the effect of the N7 substitution. Finally, ligand L6, decorated with a trifluoro benzyl group, afforded a 2:1 ligand:metal molecular complex under certain crystallization conditions. This finding, although just preliminary, could open the way to a direct control of the overall assembly process, viz. complexation vs. polymerization, by a simple structural modification of the ligand.
In questo lavoro di tesi sono stati progettati, sintetizzati e caratterizzati otto derivati bispidinici L1-L8 finalizzati alla costruzione di polimeri di coordinazione (CP). Diversamente dai più comuni ligandi bispidinici, L1-L8 presentano due azoti piridinici in posizione divergente e una funzionalità differente all’ azoto N7 dello scheletro biciclico. Lo studio strutturale di L1-L7 mediante diffrazione a raggi X su cristalli singoli (SC) ha fornito informazioni sulle interazioni che generano il packing cristallino e sulle modifiche strutturali che questi risentono quando si trovano coinvolti in interazioni di coordinazione. Ciascun ligando L1-L8 è stato fatto reagire con ioni Mn(II) in presenza di diversi solventi, attraverso metodi di cristallizzazione lenti e veloci in modo tale da ottenere CP che in seguito sono stati caratterizzati mediante tecniche di diffrazione a raggi X su cristallo singolo (SC-XRD) e su polveri (P-XRD). L’analisi strutturale di ogni CP (1·TCMSC, 1·NBSC, 2·TCMSC, 4·TCMSC, 4·NBSC, 5·TCMSC, 5·TCM·NBSC) mostra la formazione di catene monodimensionali a nastri (ribbons), che interagiscono le une con le altre mediante interazioni deboli, diverse a seconda del tipo di ligando e del tipo di solvente ospitato. In generale, le robuste catene monodimensionali di questi polimeri di coordinazione si assemblano, attraverso interazioni inter-ribbon deboli, orientandosi le une rispetto alle altre in modi diversi, formando strutture non porose oppure aventi canali. Questi materiali hanno dimostrato un comportamento dinamico notevole, poiché possono andare in contro a processi di scambio solido/liquido e solido/gassoso, durante i quali le catene sono sottoposte ad una significativa riorganizzazione strutturale nel momento in cui rilasciano molecole di solvente ospite e ne intrappolano di nuove. In particolare, tale comportamento dinamico è strettamente legato al tipo di ligando e al tipo di interazioni deboli presenti tra i nastri, le quali variano in base ai diversi sostituenti N7 presenti nella struttura e quindi, alla superficie accessibile di ogni ligando. In questo lavoro di tesi, viene presentata un'analisi dettagliata delle caratteristiche strutturali di questi nuovi CP con l’intenzione di determinare la relazione struttura-proprietà in base alla diversa sostituzione in posizione N7 della bispidina. Infine, il ligando L6, sostituito in N7 con un gruppo trifluoro benzilico, fornisce, in determinate condizioni di cristallizzazione, un complesso molecolare 2:1 ligando:metallo. Questo risultato, anche se solo preliminare, potrebbe aprire la strada ad un controllo diretto del processo complessivo di assemblaggio, cioè complessazione vs. polimerizzazione, semplicemente modificando la struttura del ligando.
Dynamic and tunable behavior of 1D bispidine-based Mn(II) coordination polymers
CAPUTO, JOSEFINA MARIA
2018/2019
Abstract
Bispidine derivatives L1-L8 were designed for being compatible with coordinative polymerization, synthesized and fully characterized. At variance with more common bispidine ligands, they possess two pyridine moieties with their N-atoms oriented in a divergent fashion and they differ from one another for the group in the N7 position of the scaffold. In-depth structural study of L1-L7 by means of X-ray diffraction on single crystals (SC) provided information as to their packing interactions and their structural modifications when involved in coordination interactions. L1-L8 were then reacted with Mn(II) ions in the presence of different solvents through slow and fast crystallization methods to build novel coordination polymers (CPs) which were characterized through single crystal (SC-XRD) and powder X-ray diffraction (P-XRD) techniques. Extensive structural analysis of CPs, namely 1·TCMSC, 1·NBSC, 2·TCMSC, 4·TCMSC, 4·NBSC, 5·TCMSC, 5·TCM·NBSC was performed, showing in all cases non-interpenetrated 1D ribbon chains, which interacted with each other through ribbon-ribbon packing interactions, according to the ligand’s identity and the trapped solvents. In general, these CPs are assembled via weak inter-ribbon interactions among very robust 1D chains that can arrange one with respect to the others in several orientations, forming channeled as well as non-porous structures. These materials showed a remarkable dynamic behavior as they can undergo solid/liquid and solid/gas guest-exchange processes where ribbon chains are subjected to significant structural re-organization by releasing trapped solvent molecules and accommodating new ones. Notably, such dynamic behavior is dependent on the ligand employed and this was attributed to the extent of inter-ribbon interactions present in the CP which varies due to the presence of different N7 substituents. In this thesis, we present a detailed analysis of the structural features of these novel CPs aiming to determine a structure-property relationship based on the effect of the N7 substitution. Finally, ligand L6, decorated with a trifluoro benzyl group, afforded a 2:1 ligand:metal molecular complex under certain crystallization conditions. This finding, although just preliminary, could open the way to a direct control of the overall assembly process, viz. complexation vs. polymerization, by a simple structural modification of the ligand.| File | Dimensione | Formato | |
|---|---|---|---|
|
2019_04_Caputo.pdf
solo utenti autorizzati dal 04/04/2020
Descrizione: Testo della tesi
Dimensione
23.51 MB
Formato
Adobe PDF
|
23.51 MB | Adobe PDF | Visualizza/Apri |
I documenti in POLITesi sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/10589/145995