GRATITUDE ET BIEN-ÊTRE SOCIAL : MÉCANISMES EXPLICATIFS DES EFFETS DE LA GRATITUDE SUR LE BIEN-ÊTRE INDIVIDUEL ET COLLECTIF

La gratitude a été définie comme une émotion sociale agréable qui génère de nombreuses conséquences positives sur la santé physique, mentale et sociale par le biais d’une augmentation de la capacité à apprécier les expériences, à percevoir des bénéfices même en cas d’adversité, et à développer, maintenir et améliorer les relations sociales. Toutefois, loin d’être un état dont les effets ne bénéficieraient qu’à l’individu, la gratitude engendre également des effets bénéfiques pour autrui, notamment par le biais de son expression : l’expression de gratitude génère un sentiment d’utilité et de valeur sociale chez l’interlocuteur, augmentant par-là le bien-être psychologique. Au-delà du simple effet de contagion émotionnelle, la gratitude entraîne une amélioration réciproque des relations, ce qui favorise le maintien ou l’amélioration des relations sociales constructives, auxquelles le bien-être est étroitement lié. Les mécanismes explicatifs des liens entre gratitude et bien-être individuel et collectif sont présentés, ainsi que des perspectives de recherche et d’applications pratiques.Gratitude has been defined as a social emotion which generates numerous positive consequences on physical, mental and social well-being through the development of the ability to savor experiences, to find benefits even when facing adversity, and to develop, maintain, and increase positive relationships. However, far from leading to a state in which the effects would only benefit the individual, gratitude generates beneficial effects for others as well. Expressing gratitude generates feelings of social utility and social worth which positively impact psychological well-being of the receiving party. Beyond emotional contagion, through which relatives benefit from others’ positive emotions, gratitude opens a pathway that nurtures mutual positive relationships, thereby ensuring maintenance or increased well-being. The present article explains the mechanisms through which gratitude positively impacts individual and collective well-being, and presents further research and practical avenues

Suppressing Cyclic Polymerization for Isoselective Synthesis of High-Molecular-Weight Linear Polylactide Catalyzed by Sodium/Potassium Sulfonamidate Complexes

A new sodium/potassium crown ether complex system with a series of bichelating sulfonamides as ligands was developed for the ring-opening polymerization (ROP) of <i>rac</i>-lactide. In this system, the side reaction of cyclic polymerization can be suppressed very well because of very different ROP rates initiated by BnOH and sulfonamide anion. The synthesis of high molecular weight linear polylactide with molecular weight high up to 107 kg/mol was successful. The best isoselectivity also can reach to a high value of <i>P</i>_m = 0.84. The NMR analysis of the reaction mixture of <i>rac</i>-lactide and complex <b>3</b> together with kinetic studies suggests the mechanism of ROP in the absence of alcohol is a coordination–insertion mechanism. After addition of BnOH, the ROP rate can increase remarkably due to the cooperation interaction of alcohol and complex <b>3</b>

Alkali-Metal Monophenolates with a Sandwich-Type Catalytic Center as Catalysts for Highly Isoselective Polymerization of <i>rac</i>-Lactide

Highly isoselective ring-opening polymerization (ROP) of <i>rac</i>-lactide is a challenge for sodium and potassium complexes under mild conditions. In this work, three sodium and potassium complexes with a sandwich-type catalytic center are highly active catalysts for the polymerization of <i>rac</i>-lactide and show high isoselectivities with <i>P</i>_<i>m</i> values of 0.72–0.82. The best isoselectivity of <i>P</i>_<i>m</i> = 0.82 is the highest value for alkali-metal complexes under mild conditions. The molecular weights of the obtained PLA are close to the theoretical values, and the molecular weight distributions are narrow

Highly Iso-Selective and Active Catalysts of Sodium and Potassium Monophenoxides Capped by a Crown Ether for the Ring-Opening Polymerization of <i>rac</i>-Lactide

Sodium and potassium complexes supported by a bulky monophenoxy with one xanthenyl group at the ortho-position and 18-crown-6 or 15-crown-5 as an auxiliary ligand were synthesized and characterized. These complexes are highly iso-selective and active catalysts for the controlled ring-opening polymerization of <i>rac</i>-lactide. The best isotacticity (<i>P</i>_m) achieved was 0.86, which is the highest iso-selectivity reported to date for an alkali-metal complex. In addition, the corresponding polymer exhibited a high <i>T</i>_m of 182 °C. Furthermore, the polymerization looks like an anti-Arrhenius reaction, which is slower at high temperatures than at low temperatures

Suppressing Cyclic Polymerization for Isoselective Synthesis of High-Molecular-Weight Linear Polylactide Catalyzed by Sodium/Potassium Sulfonamidate Complexes

A new sodium/potassium crown ether complex system with a series of bichelating sulfonamides as ligands was developed for the ring-opening polymerization (ROP) of <i>rac</i>-lactide. In this system, the side reaction of cyclic polymerization can be suppressed very well because of very different ROP rates initiated by BnOH and sulfonamide anion. The synthesis of high molecular weight linear polylactide with molecular weight high up to 107 kg/mol was successful. The best isoselectivity also can reach to a high value of <i>P</i>_m = 0.84. The NMR analysis of the reaction mixture of <i>rac</i>-lactide and complex <b>3</b> together with kinetic studies suggests the mechanism of ROP in the absence of alcohol is a coordination–insertion mechanism. After addition of BnOH, the ROP rate can increase remarkably due to the cooperation interaction of alcohol and complex <b>3</b>

Suppressing Cyclic Polymerization for Isoselective Synthesis of High-Molecular-Weight Linear Polylactide Catalyzed by Sodium/Potassium Sulfonamidate Complexes

A new sodium/potassium crown ether complex system with a series of bichelating sulfonamides as ligands was developed for the ring-opening polymerization (ROP) of <i>rac</i>-lactide. In this system, the side reaction of cyclic polymerization can be suppressed very well because of very different ROP rates initiated by BnOH and sulfonamide anion. The synthesis of high molecular weight linear polylactide with molecular weight high up to 107 kg/mol was successful. The best isoselectivity also can reach to a high value of <i>P</i>_m = 0.84. The NMR analysis of the reaction mixture of <i>rac</i>-lactide and complex <b>3</b> together with kinetic studies suggests the mechanism of ROP in the absence of alcohol is a coordination–insertion mechanism. After addition of BnOH, the ROP rate can increase remarkably due to the cooperation interaction of alcohol and complex <b>3</b>

Synthesis and Characterization of Multi-Alkali-Metal Tetraphenolates and Application in Ring-Opening Polymerization of Lactide

A series of alkali metal complexes supported by two bulky tetraphenols were synthesized and characterized. The reactions of α,α,α′,α′-tetra­(3,5-di-<i>tert</i>-butyl-2-hydroxyphenyl)-<i>p</i>-xylene­(<i>para</i>-tetraphenol) with ^<i>n</i>BuLi, sodium, and KSi­(NMe₂)₃ gave bimetallic complexes <b>1</b>, <b>2</b>, and <b>3</b>, respectively. Treatments of the α,α,α′,α′-tetra­(3,5-di-<i>tert</i>-butyl-2-hydroxyphenyl)-<i>m</i>-xylene­(<i>meta</i>-tetraphenol) with 2 or 4 equiv of ^<i>n</i>BuLi afforded complexes <b>4</b> or <b>5</b>, while the reactions of <i>meta</i>-tetraphenol with sodium and KSi­(NMe₂)₃ gave only trimetallic complexes <b>6</b> and <b>7</b> for the additional p−π interaction. Complexes <b>1</b>–<b>7</b> were all characterized by single-crystal X-ray diffraction techniques. In the presence of benzyl alcohol, all complexes are active catalysts for the ring-opening polymerization of l-lactide. Comparatively, bimetallic complexes <b>1</b>, <b>2</b>, and <b>3</b> are more efficient catalysts because of their symmetric structures, in which complex <b>3</b> presents as a rare highly active potassium catalyst for the ring-opening polymerization of lactide, leading to polymers with good molecular weight control and narrow molecular weight distributions

Alternating Sequence Controlled Copolymer Synthesis of α‑Hydroxy Acids via Syndioselective Ring-Opening Polymerization of <i>O</i>‑Carboxyanhydrides Using Zirconium/Hafnium Alkoxide Initiators

The ring-opening polymerization (ROP) of <i>O</i>-carboxyanhydrides (OCAs) can give diverse poly­(α-hydroxy acid)­s (PAHAs) with different functional groups because of easy modification of the side group of OCAs, which can extend applications of PAHAs widely. The stereoselective polymerization of <i>O</i>-carboxyanhydrides and further sequence controlled alternating copolymerization of OCAs were still big challenges until now for lack of suitable catalysts/initiators. In this work, a highly syndioselective ROP of OCAs system as the first stereoselective example in this area is reported using zirconium/hafnium alkoxides as initiators with the highest <i>P</i>_r value up to 0.95. Furthermore, these initiators were successfully applied in the precisely alternating sequence controlled copolymerization of PheOCA and Tyr­(Bn)­OCA, and alternating copolymerization of LacOCA and PheOCA was also achieved

Stereoselective Alkali-Metal Catalysts for Highly Isotactic Poly(<i>rac</i>-lactide) Synthesis

A high degree of chain end control in the isoselective ring-opening polymerization (ROP) of <i>rac-</i>lactide is a challenging research goal. In this work, eight highly active sodium and potassium phenolates as highly isoselective catalysts for the ROP of <i>rac-</i>lactide are reported. The best isoselectivity value of <i>P</i>_m = 0.94 is achieved. The isoselective mechanism is chain-end control through the analysis of the stereoerrors in the microstructure of a final polymer; thus, isotactic multiblock structure polymers are obtained, and the highest melt point can reach 192.5 °C. The donating group in phenolate can clearly accelerate the ROP reaction, potassium complexes are more active than the analogous sodium complexes, and the big spacial hindrance of the ligand can decrease the activity. The high isoselectivities of these complexes mostly result from their sandwich structure constructed by the plane of the crown and the plane of the anthryl group

Synthesis and Characterization of Multi-Alkali-Metal Tetraphenolates and Application in Ring-Opening Polymerization of Lactide

A series of alkali metal complexes supported by two bulky tetraphenols were synthesized and characterized. The reactions of α,α,α′,α′-tetra­(3,5-di-<i>tert</i>-butyl-2-hydroxyphenyl)-<i>p</i>-xylene­(<i>para</i>-tetraphenol) with ^<i>n</i>BuLi, sodium, and KSi­(NMe₂)₃ gave bimetallic complexes <b>1</b>, <b>2</b>, and <b>3</b>, respectively. Treatments of the α,α,α′,α′-tetra­(3,5-di-<i>tert</i>-butyl-2-hydroxyphenyl)-<i>m</i>-xylene­(<i>meta</i>-tetraphenol) with 2 or 4 equiv of ^<i>n</i>BuLi afforded complexes <b>4</b> or <b>5</b>, while the reactions of <i>meta</i>-tetraphenol with sodium and KSi­(NMe₂)₃ gave only trimetallic complexes <b>6</b> and <b>7</b> for the additional p−π interaction. Complexes <b>1</b>–<b>7</b> were all characterized by single-crystal X-ray diffraction techniques. In the presence of benzyl alcohol, all complexes are active catalysts for the ring-opening polymerization of l-lactide. Comparatively, bimetallic complexes <b>1</b>, <b>2</b>, and <b>3</b> are more efficient catalysts because of their symmetric structures, in which complex <b>3</b> presents as a rare highly active potassium catalyst for the ring-opening polymerization of lactide, leading to polymers with good molecular weight control and narrow molecular weight distributions