Synthesis, characterization, and luminescent properties of two new Zr(IV) metal–organic frameworks based on anthracene derivatives

Metal–organic frameworks (MOFs) are crystalline materials constructed from metal ions or clusters, connected by multidentate organic ligands. Herein, we describe the synthesis and photophysical properties of two Zr-based, anthracene-containing MOFs, assembled from 2,6-anthracenedicarboxylic acid (2,6-ADCA and 2,6-MOF) and 1,4-anthracenedicarboxylic acid (1,4-ADCA and 1,4-MOF). The 2,6-ADCA analogue formed a highly crystalline octahedral structure that is isostructural with the well-known UiO-67 frameworks. Incorporation of the 1,4-ADCA ligand, on the other hand, resulted in large rod-shaped crystals. Both MOFs exhibit linker-based luminescence. The excited-state properties of the 2,6-MOF and 1,4-MOF were examined using stead-state diffuse reflectance and emission spectroscopies and time-correlated single photon counting (TCSPC) spectroscopy. The photophysical properties of the MOFs are compared with those of the corresponding ligand in solution.

Download Full-text

Single Point PICA Probing with an Avalanche Photo-Diode

ISTFA 2001: Conference Proceedings from the 27th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2001p0023 ◽

2001 ◽

Author(s):

Mike Bruce ◽

Rama R. Goruganthu ◽

Shawn McBride ◽

David Bethke ◽

J.M. Chin

Keyword(s):

Single Photon ◽

Single Point ◽

Photon Counting ◽

Ring Oscillator ◽

Time Resolved ◽

Single Photon Counting ◽

Photo Diode ◽

Avalanche Photo Diode ◽

Photo Multiplier Tube ◽

Channel Plate

Abstract For time resolved hot carrier emission from the backside, an alternate approach is demonstrated termed single point PICA. The single point approach records time resolved emission from an individual transistor using time-correlated-single-photon counting and an avalanche photo-diode. The avalanche photo-diode has a much higher quantum efficiency than micro-channel plate photo-multiplier tube based imaging cameras typically used in earlier approaches. The basic system is described and demonstrated from the backside on a ring oscillator circuit.

Download Full-text

Exciton Coupling and Conformational Changes Impacting the Excited State Properties of Metal Organic Frameworks

Molecules ◽

10.3390/molecules25184230 ◽

2020 ◽

Vol 25 (18) ◽

pp. 4230

Author(s):

Andreas Windischbacher ◽

Luca Steiner ◽

Ritesh Haldar ◽

Christof Wöll ◽

Egbert Zojer ◽

...

Keyword(s):

Conformational Changes ◽

Photophysical Properties ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Red Shift ◽

Light Emitting ◽

Light Emitting Devices ◽

Exciton Coupling ◽

Metal Organic ◽

Crystalline Metal

In recent years, the photophysical properties of crystalline metal-organic frameworks (MOFs) have become increasingly relevant for their potential application in light-emitting devices, photovoltaics, nonlinear optics and sensing. The availability of high-quality experimental data for such systems makes them ideally suited for a validation of quantum mechanical simulations, aiming at an in-depth atomistic understanding of photophysical phenomena. Here we present a computational DFT study of the absorption and emission characteristics of a Zn-based surface-anchored metal-organic framework (Zn-SURMOF-2) containing anthracenedibenzoic acid (ADB) as linker. Combining band-structure and cluster-based simulations on ADB chromophores in various conformations and aggregation states, we are able to provide a detailed explanation of the experimentally observed photophysical properties of Zn-ADB SURMOF-2: The unexpected (weak) red-shift of the absorption maxima upon incorporating ADB chromophores into SURMOF-2 can be explained by a combination of excitonic coupling effects with conformational changes of the chromophores already in their ground state. As far as the unusually large red-shift of the emission of Zn-ADB SURMOF-2 is concerned, based on our simulations, we attribute it to a modification of the exciton coupling compared to conventional H-aggregates, which results from a relative slip of the centers of neighboring chromophores upon incorporation in Zn-ADB SURMOF-2.

Download Full-text

UVscope and its application aboard the ASTRI-Horn telescope

Experimental Astronomy ◽

10.1007/s10686-021-09728-6 ◽

2021 ◽

Author(s):

Maria Concetta Maccarone ◽

Giovanni La Rosa ◽

Osvaldo Catalano ◽

Salvo Giarrusso ◽

Alberto Segreto ◽

...

Keyword(s):

Gamma Ray ◽

Single Photon ◽

Photon Counting ◽

Light Flux ◽

Cosmic Ray ◽

High Energy ◽

Wide Field ◽

High Energy Astrophysics ◽

Single Photon Counting ◽

Photon Counting Mode

AbstractUVscope is an instrument, based on a multi-pixel photon detector, developed to support experimental activities for high-energy astrophysics and cosmic ray research. The instrument, working in single photon counting mode, is designed to directly measure light flux in the wavelengths range 300-650 nm. The instrument can be used in a wide field of applications where the knowledge of the nocturnal environmental luminosity is required. Currently, one UVscope instrument is allocated onto the external structure of the ASTRI-Horn Cherenkov telescope devoted to the gamma-ray astronomy at very high energies. Being co-aligned with the ASTRI-Horn camera axis, UVscope can measure the diffuse emission of the night sky background simultaneously with the ASTRI-Horn camera, without any interference with the main telescope data taking procedures. UVscope is properly calibrated and it is used as an independent reference instrument for test and diagnostic of the novel ASTRI-Horn telescope.

Download Full-text

Porphyrin MOF-Derived Porous Carbons: Preparation and Applications

C – Journal of Carbon Research ◽

10.3390/c7020047 ◽

2021 ◽

Vol 7 (2) ◽

pp. 47

Author(s):

Flávio Figueira ◽

Filipe A. Almeida Paz

Keyword(s):

Chemical Composition ◽

Carbon Material ◽

Metal Organic Frameworks ◽

Electrochemical Reactions ◽

Porous Carbon Material ◽

Important Class ◽

Porous Carbons ◽

Preparation Methods ◽

Crystalline Materials ◽

Metal Organic

Metal–organic frameworks (MOFs) are crystalline materials with permanent porosity, composed of metal nodes and organic linkers whose well-ordered arrangement enables them to act as ideal templates to produce materials with a uniform distribution of heteroatom and metal elements. The hybrid nature of MOFs, well-defined pore structure, large surface area and tunable chemical composition of their precursors, led to the preparation of various MOF-derived porous carbons with controlled structures and compositions bearing some of the unique structural properties of the parent networks. In this regard, an important class of MOFs constructed with porphyrin ligands were described, playing significant roles in the metal distribution within the porous carbon material. The most striking early achievements using porphyrin-based MOF porous carbons are here summarized, including preparation methods and their transformation into materials for electrochemical reactions.

Download Full-text