Upconversion Luminescence through Cooperative and Energy‐Transfer Mechanisms in Yb³⁺‐Metal‐Organic Frameworks

Abstract

Lanthanide-doped metal-organic frameworks (Ln-MOFs) have versatile luminescence properties, however it is challenging to achieve lanthanide-based upconversion luminescence in these materials. Here, 1,3,5-benzenetricarboxylic acid (BTC) and trivalent Yb 3 + ions were used to generate crystalline Yb-BTC MOF 1D-microrods with upconversion luminescence under near infrared excitation via cooperative luminescence. Subsequently, the Yb-BTC MOFs were doped with a variety of different lanthanides to evaluate the potential for Yb 3 + -based upconversion and energy transfer. Yb-BTC MOFs doped with Er 3 + , Ho 3 + , Tb 3 + , and Eu 3 + ions exhibit both the cooperative luminescence from Yb 3 + and the characteristic emission bands of these ions under 980 nm irradiation. In contrast, only the 497 nm upconversion emission band from Yb 3 + is observed in the MOFs doped with Tm 3 + , Pr 3 + , Sm 3 + , and Dy 3 + . The effects of different dopants on the efficiency of cooperative luminescence were established and will provide guidance for the exploitation of Ln-MOFs exhibiting upconversion.

Unique excitation power density and pulse width-dependent multicolor upconversion emissions of Y2Mo4O15:Yb3+,Ho3+ for anti-counterfeiting and information encryption applications

“…In addition to the anti-counterfeiting application, materials with different output information under different excitation modes can be used in information encryption. [33][34][35] Taking advantage of the unchangeable PL color of NaYF 4 :40%Yb 3+ , 2%Ho 3+ microcrystals, combining Y 2 Mo 4 O 15 :40%Yb 3+ ,2%Ho 3+ microcrystals with NaYF 4 :40%Yb 3+ ,2%Ho 3+ microcrystals, a pixelated pattern (8 Â 4 dot matrix) on a quartz plate was constructed. As shown in Fig.…”

Europium(III)/Terbium(III) mixed metal-organic frameworks and their application as a ratiometric thermometer

“…1,2 Thus, MOFs have found application in easy-to-read optical sensors, [3][4][5] as well as in electrochemical sensing 6,7 and fluorescent sensing. 1,[8][9][10][11] As for other applications, MOFbased fluorescence sensors stands out compared to other materials due to their modular synthesis allowing to adjust the MOF structure and chemical composition and, thus, to tailor its properties. This has in the past allowed to design fluorescence sensors with high target selectivity as well as high sensitivities and low limit of detection.…”

“…MOF-based fluorescence sensors have found application in various fields including toxic metal ion detections in wastewater, gas and volatile organic compounds detection but also for determination of physical properties such as pH value, humidity and temperature. 1,[8][9][10][11] To allow for ratiometric sensing, that is self-calibrating sensing without the use of an external reference, at least two different luminescent centres are required. 9 This can include two different metal complexes, e.g.…”

“…Lanthanide-based MOFs are attracting increasing attention due to the high luminescence intensity and sharp emission lines of the lanthanides. 11,12 Thus, from the two (or more) transitions originating from the different emissive centres within the same material, the sensor signal is determined optically as the ratio between the probe-dependent emission intensities. In case of temperature sensing, the nature of the MOF, i.e.…”

“…In their seminal report, Guo et al reported the use of sodium acetate (NaOAc) as a suitable capping agent to reduce the particle size without affecting the crystal structure and properties of LnBTC MOFs. 19 While the original protocol allowed for the synthesis of rod-like LnBTC of several tenth of µm in length, 11,19 the protocol reported by Guo et al lead to the synthesis of almost spherical particles with diameters below 100 nm. Those LnBTC (nano)particles have found wide application in the field of luminescent sensing, including small molecule detection, 13,20 and ratiometric temperature sensing 21 or in the field of luminescent thin films.…”