Chemistry is the experimental and theoretical study of materials on their properties at both the macroscopic and microscopic levels.In a patent， Safety of 3,4,7,8-Tetramethyl-1,10-phenanthroline, Which mentioned a new discovery about 1660-93-1
DFT calculations on the complexes (M(CO)4(N,N)] (M = Cr or W; N,N = 1,10-phenanthroline (phen) or 3,4,7,8tetramethyl-l,10-phenanthroline (tmp)) have revealed that the phen and tmp complexes have different LUMOs: b, and a2, respectively. Nevertheless, the character of the low-lying MLCT electronic transitions, calculated by timedependent (TD) DFT, hardly changes on going from phen to tmp since the bt(d-4 -b,(phen/tmp) transition is the strongest, whether the b,(phen/tmp) orbital is the LUMO or not. The switching of LUMO Orbitals is manifested by the following features exhibited by the tmp complexes, as compared with their phen counterparts: slightly lower IR v(CO) frequencies, larger solvatochromism, higher relative resonance enhancement of the A,2 Raman i'(CO) peak and larger shifts of electrochemical reduction potentials from the “free” ligand value. The similar shapes and intensities of the visible absorption bands of the tmp and phen complexes and similarity of their resonance Raman spectra support the TD-DFT prediction of an essentially identical character of the electronic transition(s) responsible. Reduction of the [M(CO)4(N,N)] complexes produces the corresponding radical anions [M(CO)4(N,N)]’~, which were characterized by EPR, IR and UV-Vis spectroelectrochemistry. In contrast with the neutral species, the properties of the radical-anionic tmp and phen complexes are very different due to difference between their SOMOs: a2 and b, respectively. This is manifested by the profoundly different EPR hypefine splitting (hfs) patterns observed: [M(CO)4(phen)]’~ complexes show large hfs from the 14N donor atoms and from the pairs of ‘H atoms at C3,8 and C4,7 positions. On the other hand, EPR spectra of [M(CO)4(tmp)]’~ show large hfs from ‘H atoms of a pair of CH3 groups at C4,7 positions and two pairs of’H atoms at C2,9 and C5,6, while the 14N splitting is rather small. Reasonable agreement between experimental and DFT-calculated hfs was obtained. The switching of LUMO character between b, and a2 can have important implications for constructing molecular devices based on phen complexes. is The Royal Society of Chemistry 2000.
Because enzymes can increase reaction rates by enormous factors and tend to be very specific, Safety of 3,4,7,8-Tetramethyl-1,10-phenanthroline, typically producing only a single product in quantitative yield, they are the focus of active research.you can also check out more blogs about 1660-93-1
Reference：
Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI