Robust Yellow-Violet Pigments Tuned by Site-Selective Manganese Chromophores

Abstract

The rational design of multifunctional inorganic pigments relies on the manipulation of ionic valence and local surroundings of a chromophore in structurally and chemically habitable hosts. To date, the development of environmentally benign and intense violet/purple pigments is still a challenge. Here we report a family of A 3−x Mn x TeO 6 and A 3−2x Mn x Li x TeO 6 (A = Zn, Mg; x = 0.01−0.15) pigments colored by site-selective Mn 2+ O 4 yellow and Mn 3+ O 5−6 violet chromophores. Zn 2.9 Mn 0.1 TeO 6 is intense bright yellow, comparable with commercial BiVO 4 , and has better near-infrared reflectivity (∼89%) in comparison to commercial TiO 2 . The codoped Li + "activator" generates holes and chargebalanced Mn 3+ (Mn 3+ O 5−6 ), realizing a color transformation from yellow to the bright violet pigments of A 3−2x Mn x Li x TeO 6 . The most vivid Mg 2.8 Mn 0.1 Li 0.1 TeO 6 is probably the best violet pigment known to date, exhibits excellent chemical and thermodynamic stability, and demonstrates pressure-dependent stability up to 5−7 GPa, before a (reversible) phase transition to pink. Theoretical calculations revealed the correlation between site-preference occupancy and chromophore motifs and predicted a wide color gamut of pigments in Zn 3 TeO 6 -hosted 3d transition-metal ions other than manganese.

Visible ozone detection and removal in two-dimensional Mn(ii)-based metal–organic frameworks

“…38 Manganese (Mn) ion is an attractive chromophore with an unfilled 3d electron shell and variable oxidation states, and rich color regions could be obtained from its specific electronic transitions. 39 Considering the fact that O 3 is a strong oxidizing agent and Mn 2+ ion can be readily oxidized, Mn( ii )-MOFs could be feasible platforms for O 3 colorimetric sensing. In addition, it is well-documented that Mn-based oxides and MOFs have the ability to catalytically decompose O 3 to O 2 .…”

Calibration of local chemical pressure by optical probe

“…Optical parameters (such as absorption spectra and CIE color coordinates) of site-selective chromophore ions can echo on the local surroundings and thus sensitively probe the alteration of the corresponding crystal field under pressure [ 44 ]. Accordingly, the P chem delivered to local motifs could be sensed by the evolution of onsite optical parameters.…”

High Near-Infrared Reflective Zn1–xAxWO4 Pigments with Various Hues Facilely Fabricated by Tuning Doped Transition Metal Ions (A = Co, Mn, and Fe)

“…Currently, numerous reasons accounting for color presentation were widely investigated in scientific ways, and the main causes of coloration originated from the optical absorption in the visible region, resulting from ligand field effects around the transition metal ions in octahedral or tetrahedral geometries . Moreover, charge transfer between two atoms in a host compound was also an inducing factor of colors. , Notably, ZnWO 4 possessed irregular octahedral geometry and Zn 2+ (3d 10 ) can be possibly substituted by some transition metal ions, such as Mn 2+ (3d 5 ), Fe 3+ (3d 5 ), Co 2+ (3d 7 ), Ni 2+ (3d 8 ), and Cu 2+ (3d 9 ), which will lead to the formation of different colors. , Ni 2+ is adverse to environment protection, and Cu 2+ is relatively expensive; accordingly, both of them are ignored. Zinc tungstate, with excellent ionic conductivity, excellent physicochemical stability, and long lifetime of photogenerated carriers, has been extensively used in heterogeneous catalysts, photocatalytic decomposition of water, , and humidity sensors. − However, the ZnWO 4 compound, which is synthesized by a solution combustion method for high near-infrared reflectance pigments, has not been reported.…”

“…Significantly, colors of transition metal ions in irregular or asymmetric ligand fields were favorable for the development of novel inorganic pigments. − For example, the transition metal ion-substituted spiroffite Zn 2– x M x Te 3 O 8 (M = Co, Ni, and Cu) inorganic pigments, the Mn 2+ -doped Zn 3 TeO 6 bright yellow pigment with an excellent near-infrared reflectivity of 89%, and Co 2+ and Ni 2+ chromophore ions took up a more or less distorted octahedral site of LiPO 4 and brought about d–d electronic transitions in the visible region for colors . Thus, with the aim to develop novel colorful pigments containing transition metal ions in unusual oxidation states or irregular coordination geometries, the Co 2+ , Mn 2+ , or Fe 3+ chromophore ions are doped into an unstudied host of ZnWO 4 to synthesize multifarious inorganic pigments with high near-infrared reflectance, and the rational design will give rise to diversified colors.…”

“…11,12 Notably, ZnWO 4 possessed irregular octahedral geometry and Zn 2+ (3d 10 ) can be possibly substituted by some transition metal ions, such as Mn 2+ (3d 5 ), Fe 3+ (3d 5 ), Co 2+ (3d 7 ), Ni 2+ (3d 8 ), and Cu 2+ (3d 9 ), which will lead to the formation of different colors. 13,14 Ni 2+ is adverse to environment protection, and Cu 2+ is relatively expensive; accordingly, both of them are ignored. Zinc tungstate, with excellent ionic conductivity, excellent physicochemical stability, and long lifetime of photogenerated carriers, has been extensively used in heterogeneous catalysts, 15 photocatalytic decomposition of water, 16,17 and humidity sensors.…”