The molecular and crystal structures of N-picryl-m-phenolidine (or, 3-(2,4,6-trinitrophenylamino)phenol; TAP) were investigated by quantum chemical electronic structure calculations (including state-of-the-art fully-periodic DFT calculations for the crystal) and single crystal X-ray diffraction. The molecule of the compound has four low-energy conformers, which have calculated relative energies within 0.7 kJ mol^–1. In all conformers, an N–H^…O intramolecular hydrogen bond exists, which is established between the bridging amine moiety and one of the nitro groups of the picryl fragment, and an average angle between the two rings of ca. 55°. The crystals of the compound are monoclinic, P2₁/n space group, with a = 11.8098(3), b = 6.5706(2) and c = 16.5172(4) Å, β = 91.5640(10)°, Z = 4 and Z’ = 1, and is constituted by molecules assuming a geometry similar to that of the second most stable conformer of the isolated molecule. In the crystal, besides the N–H^…O intramolecular hydrogen bond already present for the isolated molecule, a strong intermolecular H-bond exists where the OH group works as proton donor. The geometric constrains resulting from the establishment of this strong intermolecular H-bond is suggested to be the main factor precluding the existence of easily obtainable additional crystalline phases, contrarily to what has been found for similar molecules. Single crystal polarized Raman spectra of TAP and of the three polymorphs exhibiting different colors of its analogue N-picryl-m-toluidine (2,4,6-trinitro-N-(m-tolyl)aniline; TMA), where the phenol OH group is replaced by a methyl group, were also studied at light of fully periodic first principle calculations. Both TAP and TMA belong to the family of the prominent N-picryl-p-toluidine compound, which is well-known for showing color polymorphism, the obtained results thus being also a contribution for the available knowledge about this rare and interesting phenomenon.

通过量子化学电子结构计算（包括最先进的完全-晶体的周期性 DFT 计算）和单晶 X 射线衍射。该化合物的分子具有四个低能构象异构体，计算出的相对能量在 0.7 kJ mol ^–1以内。在所有构象异构体中，存在一个 N-H ^… O 分子内氢键，它建立在桥胺部分和苦基片段的一个硝基之间，并且两个环之间的平均角度约为。55°。该化合物的晶体为单斜晶系，P 2 ₁/ n空间群，a  = 11.8098(3), b  = 6.5706(2) and c  = 16.5172(4) Å, β  = 91.5640(10)°, Z  = 4 and Z'  = 1, 由分子构成假设几何形状类似于孤立分子的第二个最稳定的构象异构体。在晶体中，除了 N-H ^...对于分离的分子，O 分子内氢键已经存在，在 OH 基团作为质子供体的地方存在强分子间氢键。这种强分子间氢键的建立导致的几何约束被认为是排除容易获得的额外结晶相存在的主要因素，这与对类似分子的发现相反。TAP 和三种多晶型物的单晶偏振拉曼光谱，其类似物N-苦味基- m-甲苯胺 (2,4,6-三硝基- N -( m-甲苯基）苯胺；TMA)，其中苯酚 OH 基团被甲基取代，也根据完全周期性的第一原理计算进行了研究。TAP 和 TMA 都属于著名的N-苦味基-对甲苯胺化合物家族，该化合物以显示颜色多态性而闻名，因此获得的结果也有助于了解这一罕见而有趣的现象。