  We aim to evaluate the behaviour of our 22 high-redshift (2.2 < z < 3.7) and
high-luminosity (47.39 < Lbol < 48.36) quasars in the context of the
4-Dimensional Eigenvector 1. Our approach involves studying quasar physics
through spectroscopic exploration of UV and optical emission line diagnostics.
We are using new observations from ISAAC/VLT and mainly from the SDSS to cover
the optical and the UV rest-frames, respectively. Emission lines are
characterised both through a quantitative parametrisation of the line profiles,
and by decomposing the emission line profiles using multicomponent fitting
routines. We provide spectrophotometric properties and line profile
measurements for Hb+[O iii], as well as for Si iv+O iv], C iv+He ii and the
1900 blend. Six out of the 22 objects present a significant blueshifted
component on the Hb profile, and in 14/22 cases an Hb outflowing component
associated to [O iii] is detected. The majority of [O iii] emission line
profiles show blueshifted velocities larger than 250 km s^-1. [O iii] and C iv
blueshifts show very high amplitudes and a high degree of correlation. Line
width and shift are correlated for both [O iii] and C iv, suggesting that
emission from outflowing gas is providing a substantial broadening to both
lines. Otherwise, the links between C iv centroid velocity at half intensity
(c(1/2)), Eddington ratio (L/LEdd), and bolometric luminosity are found to be
in agreement with previous studies of high-luminosity quasars. Our analysis
suggests that the behaviour of quasars of very high luminosity all along the
main sequence is strongly affected by powerful outflows involving a broad range
of spatial scales. The main sequence correlations remain valid at high redshift
and high luminosity even if a systematic increase in line width is observed.
Scaling laws based on UV Al iii and Hb emission lines are equally reliable
estimators of MBH.
