Some introductory remarks to “In memoriam of Prof. Harry R. Hudson”

Phosphoros–the Morningstar, what a wonderful world came down to us through the millennia–let us keep and protect it! And Harry Hudson was able to wander between the worlds of arts and science as well. His advice in English history and literature was well accepted, like his profound knowledge in chemistry. We teamed up as partners in a group of chemists named EUROPHOS and combined our labs in London and in Düsseldorf with syntheses, analytics, structures, NMR spectroscopy and biological aspects. We enjoyed mutual visits, supported by binational funds, and looked into α-aminophosphonic acids, α-aminophosphinic acids and corresponding esters, generally abbreviated as NHR1-CHR2-P(O)(R3)OR4. Selected results were published in a review, edited by V. Khukar and H. R. Hudson1 and in several publications.2a–j Molecular modelling, ring current calculations, and NMR were combined to understand complex 1H NMR spectra of NHPh-CHPh-P(O(OEt)2 and related structures.3 Compounds with sterically demanding substituents NH(CHPh2)-CHR-P(O(OEt)2 (R2 = Ph, Naphthyl, Anthranyl, Pyrenyl) were synthesized.4a–b Our particular interests were drawn toward the sterically overcrowded α-N-(diphenylmethyl)amino-α-(1-pyrenyl)methanephosphonic acid diethylester NH(CHPh2)-CH (Pyr)-P(O(OEt)2 which gave rise to a 1H NMR spectrum5 (Figure 1) involving a total of 29 spins (Scheme 1):