晶体数据审稿意见-为何要用OMIT指令将分辨率截低至0.84埃

DJ_Tokyo

★声明：本文仅代表个人观点，笔者学识有限，资料整理过程中难免存在疏漏谬误，请不吝指正。

晶体数据审稿意见-为何要用OMIT指令将分辨率截低至0.84埃

案例来源：CCDC [1]: 2416520. DOI [2]: 10.5517/ccdc.csd.cc2m3l8m.(Acta Cryst. 2025, C81, 82–92. DOI: 10.1107/S2053229625000282.)

案例结构如图1所示（由ChemBioDraw [3]绘制）。

▲图1 案例结构

审稿意见：

Data on these compoundswere collected to two-theta = 55°, whereas the structures presented use only data totwo-theta = 50°, without any comment on theirreasons. I calculate that about 50% of reflections between 50° and 55° have I > 2σfor 1 and 2. Normally, one would not abandon such data. Theauthors have made their unmerged hkl data available, which is commendable.

However, for all threestructures, only some of the data between two-theta = 50° and 55° is given, again without comment. The authors should explain theirreasons for these two decisions, or else correct them.

大意：

这些化合物收集到2θ = 55°，而所呈现的结构仅使用2θ = 50°的数据，对其原因未作任何解释。我计算出，对于化合物1和2，在50°至55°之间，大约50%的衍射点具有I > 2σ的强度。通常，人们不会放弃这些数据。作者提供了未合并的hkl数据，这值得称赞。

然而，对于所有三个结构，只给出了部分2θ在50°至55°之间的数据，同样没有解释。作者应该解释他们做出这两个决定的原因，否则需要纠正。

如图2所示（由Olex2 [4]呈现），ins文件中有一条SHELXL [5]指令“OMIT -3 50”（参阅推文“SHELXL指令之OMIT”）将2θ截断在50°，即将分辨率截断在0.84Å（参阅推文“单晶X射线的分辨率”）。

▲图2 案例结构投稿时状态

将ins中“OMIT -3 50”指令删除，精修，hkl文件的分辨率是0.76 Å（2θ = 55.5°），如图3所示，点击信噪比色块可以显示“I/σ(I) vs. Resolution”（信噪比随分辨率变化图），水平有一条线“3 sigma line (noise below, data above)”（3σ线（线下为噪音，线上为数据）），最右侧三个红色方框（约52°至55.5°）基本上处在该线上。

▲图3 hkl文件的分辨率

也可以在XPREP [6]中查看统计数据，如图4所示，分辨率低于0.77 Å的信噪比大于等于3.11，分辨率0.76 Å至0.77 Å区间的信噪比也达到了2.09（高于2.0为有效数据，参阅推文“审稿意见-晶体数据的“真实分辨率””），所以从信噪比上来说，完全没有理由用OMIT指令截去0.76 Å至0.84 Å（即2θ为50°至55°）区间的数据（能说得过去的理由大概就是这部分数据的完整度偏低）。

▲图4 统计数据

既然没有理由进行分辨率截断，那这个审稿意见的处理就很简单，即删除ins文件中截断分辨率的OMIT指令即可，如图5所示。

▲图5 案例结构发表时状态

相关视频：

单晶结构解析练习717(文献案例-审稿意见)：https://www.bilibili.com/video/BV1GJBzB4EMF

如需数据进行练习，请从以下链接下载：

论文PDF+CIF：

链接:https://pan.baidu.com/s/1NS4ReD4-J7H8jDWrROMTGA?pwd=yeye

提取码: yeye

晶体数据：

链接:https://pan.baidu.com/s/1qbBR7Xa2Oi1KW-ty5iJzaA?pwd=nfnn

提取码: nfnn

参考文献

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