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Rock-physics models for carbonate reservoirs assume that the mineral elastic moduli are known variables. A review of publications reveals a range of values for calcite that are out of date and misleading. We present a robust compilation for future investigations. We subsequently discuss the application of calcite elastic moduli for rock-physics modeling and interpretation of wireline data through a case study data set from an offshore Canada carbonate reservoir. The data set exhibits an offset between the zero-porosity intercept and the calcite elastic moduli values. Our experience indicates that this phenomenon is present in many wireline data sets from carbonate reservoirs around the world. We demonstrate that the data can be reconciled to the mineral elastic moduli through the interpretation of microcracks in the formation (defined by a crack density of 0.06). Understanding the microcrack effect in relatively low-porosity formations is important for the correct calibration of pore microstructure parameters and for fluid-substitution calculations. Results in the case study data set show a relatively high sensitivity to changes in fluid saturation. The sensitivity can be reduced through the use of effective mineral elastic moduli that are derived from the data. We justify the effective mineral elastic moduli as a representationmore »of the mineral moduli plus microcracks. The effective mineral elastic moduli are proposed as a relatively simple method to constrain the fluid substitution calculations in low-porosity formations where microcracks are present.« less

The design of deep-red to near-infrared (DR-NIR) phosphorescent compounds with high photoluminescence quantum yields ( Φ PL ) is a significant fundamental challenge that impacts applications including optoelectronic devices, imaging, and sensing. Here we show that bis-cyclometalated iridium complexes with electron-rich ancillary ligands can have exceptional quantum yields for DR-NIR phosphorescence (peak λ > 700 nm). Six bis-cyclometalated iridium( iii ) complexes with DR-NIR phosphorescence are described in this work, pairing highly conjugated cyclometalating ligands with electron-rich and sterically encumbered β-ketoiminate (acNac), β-diketiminate (NacNac), and N , N ′-diisopropylbenzamidinate (dipba) ancillary ligands. The photoluminescence spectra and quantum yields are solvent-dependent, consistent with significant charge-transfer character in the emissive excited state. The ancillary ligands perturb the excited-state kinetics relative to closely related compounds, which can lead to enhanced Φ PL values in the DR-NIR region, particularly in toluene solution and in doped polymer films.

2-R-1 H -1,3-Benzazaphospholes (R-BAPs) are an interesting class of σ 2 P heterocycles containing PC bonds. While closely related 2-R-1,3-benzoxaphospholes (R-BOPs) have been shown to be highly photoluminescent materials depending on specific R substituents, photoluminescence of R-BAPs has been previously limited to an example having a fused carbazole ring system. Here we detail the synthesis and structural characterization of a new R-BAP (3c, R = 2,2′-dithiophene), and compare its photoluminescence against two previously reported R-BAPs (3a, R, R′ = Me and 3b, R = 2-thiophene). The significant fluorescence displayed by the thiophene derivatives 3b ( φ = 0.53) and 3c ( φ = 0.12) stands in contrast to the weakly emissive methyl substituted analogue 3a ( φ = 0.08). Comparative computational investigations of 3a–c offer insights into the interplay between structure–function relationships affecting excited state relaxation processes.

Photoredox catalysis has been prominent in many applications, including solar fuels, organic synthesis, and polymer chemistry. Photocatalytic activity directly depends on the photophysical and electrochemical properties of photocatalysts in both the ground state and excited state. Controlling those properties, therefore, is imperative to achieve the desired photocatalytic activity. Redox potential is one important factor that impacts both the thermodynamic and kinetic aspects of key elementary steps in photoredox catalysis. In many challenging reactions in organic synthesis, high redox potentials of the substrates hamper the reaction, leading to slow conversion. Thus, the development of photocatalysts with extreme redox potentials, accompanied by potent reducing or oxidizing power, is required to execute high-yielding thermodynamically demanding reactions. In this review, we will introduce strategies for accessing extreme redox potentials in photocatalytic transformations. These include molecular design strategies for preparing photosensitizers that are exceptionally strong ground-state or excited-state reductants or oxidants, highlighting both organic and metal-based photosensitizers. We also outline methodological approaches for accessing extreme redox potentials, using two-photon activation, or combined electrochemical/photochemical strategies to generate potent redox reagents from precursors that have milder potentials.