Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high ...

KU Leuven

&#x70ED;&#x5904;&#x7406;&#x7684; Ag (+)-&#x4EA4;&#x6362;&#x6CB8;&#x77F3;&#x4EA7;&#x91CF;&#x79BB;&#x6563;&#x9AD8;&#x5EA6; photostable &#x53D1;&#x5149;&#x6CA1;&#x6709;&#x91D1;&#x5C5E;&#x7EB3;&#x7C73;&#x7C92;&#x5B50;&#x7684;&#x5F62;&#x6210;&#x7FA4;&#x96C6;&#x3002;&#x53D1;&#x73B0;&#x6709;&#x4E0D;&#x540C;&#x7C7B;&#x578B;&#x7684;&#x7279;&#x6027;&#x53D1;&#x5149;&#x989C;&#x8272;&#x4E0E;&#x53D1;&#x5C04;&#x5668;&#xFF0C;cocation&#x3001; &#x4EA4;&#x6362;&#x4E86;&#x94F6;&#x3001; &#x91CF;&#x548C;&#x4E3B;&#x673A;&#x62D3;&#x6251;&#x6027;&#x8D28;&#x800C;&#x5B9A;&#x3002;LTA &#x6837;&#x54C1;&#x4E2D;&#x5360;&#x4E3B;&#x5BFC;&#x5730;&#x4F4D;&#x7684;&#x6392;&#x653E;&#x5E26;&#x4F4D;&#x4E8E;&#x5468;&#x56F4; 550 &#x548C; 690 nm &#x7684;&#x6837;&#x54C1;&#xFF0C;&#x5206;&#x522B;&#x4F4E;&#x548C;&#x9AD8;&#x94F6;&#x5185;&#x5BB9;&#xFF0C;&#x800C;&#x5728;&#x6D41;&#x6D6E;&#x5C71;&#x578B;&#x6750;&#x6599;&#x4E2D;&#x53EA;&#x6709;&#x4E00;&#x9879;&#x5E7F;&#x6CDB;&#x7684;&#x5BBD;&#x5E26;&#x7EA6; 550 nm &#x89C2;&#x5BDF;&#x5230;&#xFF0C;&#x4E0D;&#x8BBA;&#x5728;&#x7A0B;&#x5EA6;&#x4E0A;&#x7684;&#x4EA4;&#x6D41;&#x3002;Esr &#x7ED3;&#x5408;&#x7684;&#x8367;&#x5149;&#x7279;&#x6027;&#x7684;&#x5206;&#x6790;&#x8868;&#x660E;&#x5177;&#x6709;&#x53CC;&#x91CD;&#x7535;&#x5B50;&#x57FA;&#x6001;&#x7684; Ag(6)(+) &#x7FA4;&#x96C6;&#x662F; 690 nm &#x53D1;&#x5C04;&#x5668;&#xFF0C;&#x6709;&#x51E0;&#x4E2A;&#x51E0;&#x767E;&#x5FAE;&#x79D2;&#x7684;&#x8870;&#x53D8;&#x7684;&#x5916;&#x89C2;&#x4E0E;&#x76F8;&#x5173;&#x8054;&#x3002;&#x6682;&#x65F6;&#xFF0C;&#x7EB3;&#x79D2;&#x7EA7;&#x8870;&#x51CF; 550 nm &#x53D1;&#x5C04;&#x5668;&#x88AB;&#x5206;&#x914D;&#x5230; Ag(3)(+) &#x7FA4;&#x96C6;&#x3002;&#x8FD9;&#x7C7B;&#x65B0;&#x7684; photostable &#x53D1;&#x5149;&#x7C92;&#x5B50;&#x7684;&#x53EF;&#x8C03;&#x8C10;&#x53D1;&#x5C04;&#x989C;&#x8272;&#x63D0;&#x4F9B;&#x4E86;&#x6709;&#x8DA3;&#x7684;&#x89C2;&#x70B9;&#xFF0C;&#x80DE;&#x5185;&#x6210;&#x50CF;&#x7684;&#x751F;&#x7269;&#x76F8;&#x5BB9;&#x6027;&#x6807;&#x7B7E;&#x7B49;&#x5404;&#x79CD;&#x5E94;&#x7528;&#x3002;

&#x8367;&#x5149;&#x70ED;&#x5904;&#x7406;&#x94F6;&#x4EA4;&#x6362;&#x6CB8;&#x77F3;&#x7684;&#x8868;&#x5F81;&#x3002;

Thermal treatment of Ag(+)-exchanged zeolites yields discrete highly photostable luminescent clusters without formation of metallic nanoparticles. Different types of emitters with characteristic luminescence colors are observed, depending on the nature of the cocation, the amount of exchanged silver, and the host topology. The dominant emission bands in LTA samples are situated around 550 and 690 nm for the samples with, respectively, low and high silver content, while in FAU-type materials only a broad band around 550 nm is observed, regardless of the degree of exchange. Analysis of the fluorescent properties in combination with ESR spectroscopy suggests that a Ag(6)(+) cluster with doublet electronic ground state is associated with the appearance of the 690-nm emitter, having a decay of a few hundred microseconds. Tentatively, the nanosecond-decaying 550-nm emitter is assigned to the Ag(3)(+) cluster. This new class of photostable luminescent particles with tunable emission colors offers interesting perspectives for various applications such as biocompatible labels for intracellular imaging.

Characterization of fluorescence in heat-treated silver-exchanged zeolites.

Traitement thermique de Ag (+)-&#xE9;chang&#xE9;es rendements z&#xE9;olites discr&#xE8;tes hautement photostable grappes luminescents sans formation de nanoparticules m&#xE9;talliques. Diff&#xE9;rents types d&#x26;#39;&#xE9;metteurs avec des couleurs de luminescence caract&#xE9;ristiques sont observ&#xE9;es, en fonction de la nature de l&#x26;#39;cocation, la quantit&#xE9; d&#x26;#39;argent &#xE9;chang&#xE9;es, et la topologie h&#xF4;te. Les bandes d&#x26;#39;&#xE9;mission dominantes dans des &#xE9;chantillons LTA sont situ&#xE9;s pr&#xE8;s de 550 et 690 nm pour les &#xE9;chantillons avec, respectivement, la teneur en argent basse et haute, tandis que dans les mat&#xE9;riaux de type FAU qu&#x26;#39;une large bande autour de 550 nm est observ&#xE9;e, ind&#xE9;pendamment du degr&#xE9; d&#x26;#39;&#xE9;change. L&#x26;#39;analyse des propri&#xE9;t&#xE9;s fluorescentes en combinaison avec la spectroscopie ESR indique qu&#x26;#39;une Ag (6) (+) grappe &#xE0; l&#x26;#39;&#xE9;tat doublet &#xE9;lectronique fondamental est associ&#xE9; &#xE0; l&#x26;#39;apparition de l&#x26;#39;&#xE9;metteur-690 nm, ayant une d&#xE9;croissance de quelques centaines de microsecondes. Provisoirement, la nanoseconde-d&#xE9;composition de 550 nm d&#x26;#39;&#xE9;metteur est affect&#xE9; &#xE0; la grappe Ag (3) (+). Cette nouvelle classe de particules luminescentes photostables avec des couleurs d&#x26;#39;&#xE9;mission accordables offre des perspectives int&#xE9;ressantes pour des applications diverses telles que les &#xE9;tiquettes biocompatibles pour l&#x26;#39;imagerie intracellulaire.

Caract&#xE9;risation de la fluorescence dans les trait&#xE9;s thermiquement Argent-z&#xE9;olithes &#xE9;chang&#xE9;es

W&auml;rmebehandlung von Ag (+)-Zeolithe Renditen diskrete ausgetauscht hoch lichtbest&auml;ndig leuchtende Cluster ohne Bildung von metallischen Nanopartikeln. Verschiedene Arten von Emittenten mit charakteristischen Lumineszenz-Farben werden beobachtet, je nach der Art der Cocation, die Menge der ausgetauschten Silber und die Host-Topologie. Der dominante Emission Bands LTA Proben liegen rund 550 und 690 nm bei den Proben mit, bzw. niedrigen und hohen Silber Inhalt, w&auml;hrend im FAU-Typ Materialien nur ein breites band rund 550 nm wird beobachtet, ungeachtet des Grades des Austausches. Analyse der fluoreszierenden Eigenschaften in Kombination mit ESR-Spektroskopie zufolge ein Ag(6)(+) Cluster mit Triplett-Grundzustand der Darstellung der 690-nm-Emitter, nachdem ein Zerfall von ein paar hundert Mikrosekunden zugeordnet ist. Unter Vorbehalt, ist der Nanosekunden-verfallenden 550-nm-Emitter Ag(3)(+) Cluster zugewiesen. Diese neue Klasse lichtbest&auml;ndig leuchtende Teilchen mit einstellbare Emission Farben bietet interessante Perspektiven f&uuml;r verschiedene Anwendungen wie biokompatible Etiketten f&uuml;r intrazellul&auml;ren Imaging.

Charakterisierung der Fluoreszenz in w&auml;rmebehandelter Silber ausgetauscht Zeolithe.

Trattamento termico di Ag (+)-scambiati rendimenti zeoliti discreti altamente Fotostabili luminescenti cluster senza formazione di nanoparticelle metalliche. Diversi tipi di emettitori con colori caratteristici luminescenza si osservano, a seconda della natura della cocation, la quantit&agrave; di argento scambiato e la topologia di host. Le bande di emissione dominante nei campioni di LTA sono situate intorno a 550 e 690 nm per i campioni con, rispettivamente, basso e alto argento contenuto, mentre nei materiali FAU-tipo solo un&#39;ampia banda circa 550 nm &egrave; osservata, indipendentemente dal grado di exchange. Analisi delle propriet&agrave; fluorescenti in combinazione con spettroscopia ESR suggeriscono che un cluster di Ag(6)(+) con doppietto elettronico dello stato fondamentale &egrave; associato con la comparsa dell&#39;emettitore 690 nm, avendo un decadimento di poche centinaia di microsecondi. Provvisoriamente, l&#39;emettitore di 550 nm nanosecondo-decadente &egrave; assegnato al cluster Ag(3)(+). Questa nuova classe di particelle luminescenti Fotostabili con colori emissione sintonizzabile offre interessanti prospettive per varie applicazioni quali etichette biocompatibile per l&#39;imaging intracellulare.

Caratterizzazione di fluorescenza in zeoliti scambiati argento trattato termicamente.

Ag&#x306E;&#x71B1;&#x51E6;&#x7406;&#xFF08;+&#xFF09;&#x4EA4;&#x63DB;&#x30BC;&#x30AA;&#x30E9;&#x30A4;&#x30C8;&#x306F;&#x3001;&#x91D1;&#x5C5E;&#x30CA;&#x30CE;&#x7C92;&#x5B50;&#x3092;&#x5F62;&#x6210;&#x3059;&#x308B;&#x3053;&#x3068;&#x306A;&#x304F;&#x3001;&#x96E2;&#x6563;&#x6027;&#x306E;&#x9AD8;&#x3044;&#x5149;&#x5B89;&#x5B9A;&#x767A;&#x5149;&#x306E;&#x30AF;&#x30E9;&#x30B9;&#x30BF;&#x3092;&#x751F;&#x6210;&#x3057;&#x307E;&#x3059;&#x3002;&#x7279;&#x5FB4;&#x7684;&#x306A;&#x767A;&#x5149;&#x8272;&#x3068;&#x30A8;&#x30DF;&#x30C3;&#x30BF;&#x306E;&#x7570;&#x306A;&#x308B;&#x30BF;&#x30A4;&#x30D7;&#x306E;cocation&#x306E;&#x6027;&#x8CEA;&#x4E0A;&#x3001;&#x4EA4;&#x63DB;&#x3055;&#x308C;&#x308B;&#x9280;&#x306E;&#x91CF;&#x306F;&#x3001;&#x30DB;&#x30B9;&#x30C8;&#x30C8;&#x30DD;&#x30ED;&#x30B8;&#x306B;&#x5FDC;&#x3058;&#x3066;&#x3001;&#x89B3;&#x5BDF;&#x3055;&#x308C;&#x308B;&#x3002; FAU&#x578B;&#x6750;&#x6599;&#x306B;550nm&#x4ED8;&#x8FD1;&#x3060;&#x3051;&#x5E83;&#x3044;&#x5E2F;&#x57DF;&#x306B;&#x95A2;&#x4FC2;&#x306A;&#x304F;&#x4EA4;&#x6D41;&#x306E;&#x7A0B;&#x5EA6;&#x3001;&#x89B3;&#x5BDF;&#x3057;&#x306A;&#x304C;&#x3089;LTA&#x30B5;&#x30F3;&#x30D7;&#x30EB;&#x4E2D;&#x306E;&#x652F;&#x914D;&#x7684;&#x306A;&#x767A;&#x5149;&#x30D0;&#x30F3;&#x30C9;&#x306F;&#x3001;&#x305D;&#x308C;&#x305E;&#x308C;&#x306B;&#x30B5;&#x30F3;&#x30D7;&#x30EB;&#x306E;550&#x3068;690 nm&#x4ED8;&#x8FD1;&#x306B;&#x4F4E;&#x57DF;&#x3068;&#x9AD8;&#x9280;&#x306E;&#x542B;&#x6709;&#x91CF;&#x3092;&#x4F4D;&#x7F6E;&#x3057;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002; ESR&#x5206;&#x5149;&#x6CD5;&#x3068;&#x7D44;&#x307F;&#x5408;&#x308F;&#x305B;&#x305F;&#x86CD;&#x5149;&#x7279;&#x6027;&#x306E;&#x89E3;&#x6790;&#x306F;&#x3001;&#x6570;&#x767E;&#x30DE;&#x30A4;&#x30AF;&#x30ED;&#x79D2;&#x306E;&#x6E1B;&#x8870;&#x3092;&#x6709;&#x3059;&#x308B;&#x4E8C;&#x91CD;&#x96FB;&#x5B50;&#x57FA;&#x5E95;&#x72B6;&#x614B;&#x306E;&#x9280;&#xFF08;6&#xFF09;&#xFF08;+&#xFF09;&#x30AF;&#x30E9;&#x30B9;&#x30BF;&#x304C;690 nm&#x306E;&#x30A8;&#x30DF;&#x30C3;&#x30BF;&#x306E;&#x5916;&#x89B3;&#x306B;&#x95A2;&#x9023;&#x4ED8;&#x3051;&#x3089;&#x308C;&#x3066;&#x3044;&#x308B;&#x3053;&#x3068;&#x3092;&#x793A;&#x5506;&#x3057;&#x3066;&#x3044;&#x308B;&#x3002;&#x66AB;&#x5B9A;&#x7684;&#x306B;&#x3001;&#x30CA;&#x30CE;&#x79D2;&#x306B;&#x6E1B;&#x8870;&#x3059;&#x308B;550 nm&#x306E;&#x30A8;&#x30DF;&#x30C3;&#x30BF;&#x306F;&#x3001;Ag&#xFF08;3&#xFF09;&#xFF08;+&#xFF09;&#x30AF;&#x30E9;&#x30B9;&#x30BF;&#x306B;&#x5272;&#x308A;&#x5F53;&#x3066;&#x3089;&#x308C;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002;&#x8ABF;&#x6574;&#x53EF;&#x80FD;&#x306A;&#x767A;&#x5149;&#x8272;&#x3068;&#x5149;&#x5B89;&#x5B9A;&#x767A;&#x5149;&#x7C92;&#x5B50;&#x306E;&#x3053;&#x306E;&#x200B;&#x200B;&#x65B0;&#x3057;&#x3044;&#x30AF;&#x30E9;&#x30B9;&#x306F;&#x3001;&#x3053;&#x306E;&#x3088;&#x3046;&#x306A;&#x7D30;&#x80DE;&#x5185;&#x30A4;&#x30E1;&#x30FC;&#x30B8;&#x30F3;&#x30B0;&#x306E;&#x305F;&#x3081;&#x306E;&#x751F;&#x4F53;&#x9069;&#x5408;&#x6027;&#x30E9;&#x30D9;&#x30EB;&#x306A;&#x3069;&#x69D8;&#x3005;&#x306A;&#x30A2;&#x30D7;&#x30EA;&#x30B1;&#x30FC;&#x30B7;&#x30E7;&#x30F3;&#x306E;&#x305F;&#x3081;&#x306E;&#x8208;&#x5473;&#x6DF1;&#x3044;&#x8996;&#x70B9;&#x3092;&#x63D0;&#x4F9B;&#x3057;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002;

&#x71B1;&#x51E6;&#x7406;&#x9280;&#x4EA4;&#x63DB;&#x30BC;&#x30AA;&#x30E9;&#x30A4;&#x30C8;&#x306E;&#x86CD;&#x5149;&#x306E;&#x7279;&#x6027;

Ag&#xB294; (+)&#xC758; &#xC5F4; &#xCC98;&#xB9AC;-&#xC11D; &#xC218;&#xC775;&#xB960; &#xAC1C;&#xBCC4; &#xAD50;&#xD658; &#xAE08;&#xC18D; &#xB098;&#xB178; &#xC785;&#xC790;&#xC758; &#xD615;&#xC131; &#xC5C6;&#xC774; &#xB9E4;&#xC6B0; photostable &#xBC1C;&#xAD11; &#xD074;&#xB7EC;&#xC2A4;&#xD130;. &#xB2E4;&#xC591; &#xD55C; &#xC720;&#xD615;&#xC758; &#xD2B9;&#xC131; &#xBC1C;&#xAD11; &#xC0C9;&#xC5D0; &#xBBF8;&#xD130;&#xB294; cocation, &#xAD50;&#xD658;&#xB41C; &#xC2E4;&#xBC84; &#xAE08;&#xC561; &#xBC0F; &#xD638;&#xC2A4;&#xD2B8; &#xD1A0;&#xD3F4;&#xB85C;&#xC9C0;&#xC758; &#xD2B9;&#xC131;&#xC5D0; &#xB530;&#xB77C; &#xAD00;&#xCC30; &#xB41C;&#xB2E4;. FAU &#xD615; &#xC790;&#xB8CC;&#xB9CC; &#xBE0C;&#xB85C;&#xB4DC; &#xBC34;&#xB4DC; 550 &#xC815;&#xB3C4; &#xB3D9;&#xC548; LTA &#xC0D8;&#xD50C;&#xC5D0;&#xC11C; &#xC9C0;&#xBC30;&#xC801;&#xC778; &#xBC29;&#xCD9C; &#xBC34;&#xB4DC; 550&#xACFC; 690 nm&#xC640;, &#xAC01;&#xAC01;, &#xB0AE;&#xC740; &#xBC0F; &#xB192;&#xC740; &#xC2E4;&#xBC84; &#xCF58;&#xD150;&#xCE20;, &#xC0D8;&#xD50C;&#xC5D0; &#xB300; &#xD55C; &#xC8FC;&#xC704; &#xC704;&#xCE58; &#xD574; exchange&#xC758; &#xC815;&#xB3C4; &#xAD00;&#xACC4; &#xC5C6;&#xC774; nm&#xC5D0;&#xC11C; &#xAD00;&#xCC30; &#xB429;&#xB2C8;&#xB2E4;. ESR &#xBD84;&#xAD11;&#xD559;&#xACFC; &#xD568;&#xAED8;&#xC5D0;&#xC11C; &#xD615;&#xAD11; &#xC18D;&#xC131;&#xC758; &#xBD84;&#xC11D; doublet &#xC804;&#xC790; &#xADF8;&#xB77C;&#xC6B4;&#xB4DC; &#xC0C1;&#xD0DC;&#xC640; Ag(6)(+) &#xD074;&#xB7EC;&#xC2A4;&#xD130; &#xBA87; &#xC218;&#xBC31; &#xB9C8;&#xC774;&#xD06C;&#xB85C;&#xCD08;&#xC5D0; &#xBD95;&#xAD34; &#xD558;&#xB294; &#xB370; 690 nm &#xBBF8;&#xD130;&#xC758; &#xBAA8;&#xC591;&#xACFC; &#xC5F0;&#xAD00; &#xB098;&#xC654;&#xB2E4;. &#xAC00;&#xCE6D;, &#xB098;&#xB178;&#xCD08; &#xC369; &#xC5B4; 550 nm &#xBBF8;&#xD130; Ag(3)(+) &#xD074;&#xB7EC;&#xC2A4;&#xD130;&#xC5D0; &#xD560;&#xB2F9; &#xB429;&#xB2C8;&#xB2E4;. &#xC774; &#xC0C8;&#xB85C;&#xC6B4; &#xD074;&#xB798;&#xC2A4; photostable &#xAC00;&#xBCC0; &#xBC30;&#xAE30; &#xAC00;&#xC2A4; &#xC0C9;&#xC73C;&#xB85C; &#xBC1C;&#xAD11; &#xC785;&#xC790;&#xC758; &#xC138;&#xD3EC;&#xB0B4; &#xC774;&#xBBF8;&#xC9D5;&#xC5D0; &#xB300; &#xD55C; &#xC0DD;&#xCCB4; &#xB808;&#xC774;&#xBE14; &#xAC19;&#xC740; &#xB2E4;&#xC591; &#xD55C; &#xC751;&#xC6A9; &#xD504;&#xB85C;&#xADF8;&#xB7A8;&#xC5D0; &#xB300; &#xD55C; &#xD765;&#xBBF8;&#xB85C;&#xC6B4; &#xAD00;&#xC810;&#xC744; &#xC81C;&#xACF5;&#xD569;&#xB2C8;&#xB2E4;.

&#xC5F4;&#xB41C;&#xC740; &#xAD50;&#xD658; &#xB958;&#xC5D0;&#xC11C; &#xD615;&#xAD11;&#xC758; &#xD2B9;&#xC131; &#xBD84;&#xC11D;.

El tratamiento t&#xE9;rmico de Ag (+)-intercambiada rendimientos zeolitas discretos grupos luminiscentes altamente fotoestables sin formaci&#xF3;n de nanopart&#xED;culas met&#xE1;licas. Los diferentes tipos de emisores con colores caracter&#xED;sticos de luminiscencia se observan, dependiendo de la naturaleza de la cocation, la cantidad de plata intercambiado, y la topolog&#xED;a de anfitri&#xF3;n. Las bandas de emisi&#xF3;n predominantes en las muestras de LTA est&#xE1;n situados alrededor de 550 y 690 nm para las muestras con, respectivamente, el contenido de plata baja y alta, mientras que en materiales de tipo UAF s&#xF3;lo una banda ancha alrededor de 550 nm se observa, independientemente del grado de intercambio. El an&#xE1;lisis de las propiedades fluorescentes en combinaci&#xF3;n con ESR espectroscop&#xED;a sugiere que uno de Ag (6) (+) cluster con doblete estado electr&#xF3;nico fundamental est&#xE1; asociada con la aparici&#xF3;n del emisor 690-nm, que tiene un decaimiento de unos pocos cientos de microsegundos. Tentativamente, el nanosegundo-descomposici&#xF3;n de 550-nm emisor est&#xE1; asignado al grupo de Ag (3) (+). Esta nueva clase de part&#xED;culas luminiscentes fotoestables con los colores de las emisiones ajustables ofrece interesantes perspectivas para diversas aplicaciones, como etiquetas biocompatibles para im&#xE1;genes intracelular.

Caracterizaci&#xF3;n de fluorescencia tratada t&#xE9;rmicamente intercambiados Plata-zeolitas

Optical encoding of silver zeolite microcarriers.

In situ observation of the emission characteristics of zeolite-hosted silver species during heat treatment.

We report the formation of luminescent silver clusters in zeolites by a fast, highly accurate, and controlled activation of silver ions entrapped in sodalite cages of LTA and FAU zeolites using high-brilliance soft X-rays. The activated luminescent samples were investigated by employing a combination of stationary and time-resolved spectroscopic techniques.

X-ray irradiation-induced formation of luminescent silver clusters in nanoporous matrices.

Here we present a simple route to produce well-defined photo-reduced silver nanoparticles on TiO2 containing zeolites. We used natural and artificial irradiation sources to study their effect on the particle size distribution. The samples were investigated by electron microscopy, X-ray diffraction, fluorescence microscopy and UV-Vis diffuse reflectance spectroscopy.

Fabrication of silver nanoparticles with limited size distribution on TiO2 containing zeolites.

A novel π-conjugated triad and a polymer incorporating indolo[3,2-b]-carbazole (ICZ) and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) were synthesized via a Sonogashira coupling. Compared to the parent BODIPY the absorption and fluorescence spectrum were for both compounds broader and redshifted. The redshift of the fluorescence and the decrease of the fluorescence quantum yield and decay time upon increasing solvent polarity were attributed to the formation of a partial charge-transfer state. Upon excitation in the ICZ absorption band the ICZ fluorescence was quenched in both compounds mainly due to energy transfer to the BODIPY moiety. In a similar ICZ-π-DPP polymer (where DPP is diketopyrrolopyrrole), a smaller redshift of the absorption and fluorescence spectra compared to the parent DPP was observed. A less efficient quenching of the ICZ fluorescence in the ICZ-π-DPP polymer could be related to the unfavorable orientation of the transition dipoles of ICZ and DPP. The rate constant for energy transfer was for all compounds an order of magnitude smaller than predicted by Förster theory. While in a solid film of the triad a further redshift of the absorption maximum of nearly 100 nm was observed, no such shift was observed for the ICZ-π-BODIPY polymer.

Improved Spectral Coverage and Fluorescence Quenching in Donor-acceptor Systems Involving Indolo[3-2-b]carbazole and Boron-dipyrromethene or Diketopyrrolopyrrole.

The photoluminescence (PL) of colloidal quantum dots (QDs) is known to be sensitive to the solution pH. In this work we investigate the role played by the organic coating in determining the pH-dependent PL. We compare two types of CdSe/ZnS QDs equipped with different organic coatings, namely dihydrolipoic acid (DHLA)-capped QDs and phospholipid micelle-encapsulated QDs. Both QD types have their PL intensity quenched at acidic pH values, but they differ in terms of the reversibility of the quenching process. For DHLA-capped QDs, the quenching is nearly irreversible, with a small reversible component visible only on short time scales. For phospholipid micelle-encapsulated QDs the quenching is notably almost fully reversible. We suggest that the surface passivation by the organic ligands is reversible for the micelle-encapsulated QDs. Additionally, both coatings display pH-dependent spectral shifts. These shifts can be explained by a combination of irreversible processes, such as photo-oxidation and acid etching, and reversible charging of the QD surface, leading to the quantum-confined Stark effect (QCSE), the extent of each effect being coating-dependent. At high ionic strengths, the aggregation of QDs also leads to a spectral (red) shift, which is attributable to the QCSE and/or electronic energy transfer.

The pH-dependent photoluminescence of colloidal CdSe/ZnS quantum dots with different organic coatings.

The integration of metal atoms and clusters in well-defined dielectric cavities is a powerful strategy to impart new properties to them that depend on the size and geometry of the confined space as well as on metal-host electrostatic interactions. Here, we unravel the dependence of the electronic properties of metal clusters on space confinement by studying the ionization potential of silver clusters embedded in four different zeolite environments over a range of silver concentrations. Extensive characterization reveals a strong influence of silver loading and host environment on the cluster ionization potential, which is also correlated to the cluster's optical and structural properties. Through fine-tuning of the zeolite host environment, we demonstrate photoluminescence quantum yields approaching unity. This work extends our understanding of structure-property relationships of small metal clusters and applies this understanding to develop highly photoluminescent materials with potential applications in optoelectronics and bioimaging.

Tuning the energetics and tailoring the optical properties of silver clusters confined in zeolites.

One of the ultimate goals in the study of metal clusters is the correlation between the atomic-scale organization and their physicochemical properties. However, direct observation of the atomic organization of such minuscule metal clusters is heavily hindered by radiation damage imposed by the different characterization techniques. We present direct evidence of the structural arrangement, at an atomic level, of luminescent silver species stabilized in faujasite (FAU) zeolites using aberration-corrected scanning transmission electron microscopy. Two different silver clusters were identified in Ag-FAU zeolites, a trinuclear silver species associated with green emission and a tetranuclear silver species related to yellow emission. By combining direct imaging with complementary information obtained from X-ray powder diffraction and Rietveld analysis, we were able to elucidate the main differences at an atomic scale between luminescent (heat-treated) and nonluminescent (cation-exchanged) Ag-FAU zeolites. It is expected that such insights will trigger the directed synthesis of functional metal nanocluster-zeolite composites with tailored luminescent properties.

Eduardo Coutino-Gonzalez

Division of Molecular Imaging and Photonics,
Department of Chemistry,
Division of Molecular Imaging and Photonics, Department of Chemistry

KU Leuven

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

Eduardo Coutino-Gonzalez

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Division of Molecular Imaging and Photonics,Department of Chemistry,Division of Molecular Imaging and Photonics, Department of Chemistry

KU Leuven

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

Division of Molecular Imaging and Photonics,
Department of Chemistry,
Division of Molecular Imaging and Photonics, Department of Chemistry