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Bis‐tridentate Ir(III) metal complexes are expected to show great potential in organic light‐emitting diode (OLED) applications due to the anticipated, superb chemical and photochemical stability. Unfortunately, their exploitation has long been hampered by lack of adequate methodology and with inferior synthetic yields. This hurdle can be overcome by design of the first homoleptic, bis‐tridentate Ir(III) complex [Ir(pzpyph)(pzHpyph)] (1), for which the abbreviation (pzpyph)H (or pzHpyph) stands for the parent 2‐pyrazolyl‐6‐phenyl pyridine chelate. After that, methylation and double methylation of 1 afford the charge‐neutral Ir(III) complex [Ir(pzpyph)(pzMepyph)] (2) and cationic complex [Ir(pzMepyph)2][PF6] (3), while deprotonation of 1 gives formation of anionic [Ir(pzpyph)2][NBu4] (4), all in high yields. These bis‐tridentate Ir(III) complexes 2–4 are highly emitted in solution and solid states, while the charge‐neutral 2 and corresponding t‐butyl substituted derivative [Ir(pzpyBuph)(pzMepyBuph)] (5) exhibit superior photostability versus the tris‐bidentate references [Ir(ppy)2(acac)] and [Ir(ppy)3] in toluene under argon, making them ideal OLED emitters. For the track record, phosphor 5 gives very small efficiency roll‐off and excellent overall efficiencies of 20.7%, 66.8 cd A−1, and 52.8 lm W−1 at high brightness of 1000 cd m−2. These results are expected to inspire further studies on the bis‐tridentate Ir(III) complexes, which are judged to be more stable than their tris‐bidentate counterparts from the entropic point of view.

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. (6) was made when the 'one-pot' reaction of (phpyim- -3 -H TOC illustrationCyan-to red-emitting Ir(III) metal complexes comprising the bis-tridentate architecture, i.e. with both 2-(2,4-difluorophenyl)-6-(3-isopropyl-imidazol-2-ylidene)pyridine and functional 2-pyrazol-3-yl-6-phenylpyridine, were found to be useful for the fabrication of efficient OLEDs.

Traditionally, one of the major limitations for magnetic resonance sounding (MRS) measurement is that the weak signal generated by subsurface water molecules is prone to be disturbed by high‐level electromagnetic noise. In China, the power grid coverage is 94.6% and spiky noise and powerline harmonic noise are always present when utilizing MRS measurement in suburban areas or towns. In order to improve the performance of the MRS method, two new techniques, statistical stacking and adaptive notch filter, are introduced to remove spiky noise and power‐line harmonic noise. Firstly, four stacking procedures are analysed to suppress the natural noise and spiky noise. It could be found that statistical stacking can be utilized in the areas with serious spiky noise and can improve the signal‐to‐noise ratio by a factor of 4 to 7. Moreover, the stacking number is less than other stacking procedures and the measurement time may decrease by nearly 50% in some suburban areas or towns. Secondly, there are a variety of filtering procedures available to suppress power‐line harmonic noise, which are all based on analogue or digital notch filtering. But nearly all of them may cause distortion. An adaptive notch filter is applied here to remove power‐line harmonic noise because harmonic frequencies are away from and (or) close to the Larmor frequency, even when the frequency offset between them is zero. From simulation results, it could be noted that the signal can be recovered after adaptive notch filtering because it is not irretrievably distorted but proportionally attenuated. Thus, the amplitude attenuation can accurately be compensated. The effectiveness of the two techniques applied to MRS measurements is demonstrated by field testing with the prototype of the MRS system developed by Jilin University, China. The results show that the statistical stacking and adaptive notch filter are effective methods to remove high‐level electromagnetic noise from MRS measurements.

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