Does exist a led material that allow to interchange the emitted wavelenght in near IR spectrum?
You can't (significantly) change the wavelength of an LED, the color of the light emitted is set by the band gap which depends on the material and doping.
(You can shift it slightly with temperature and overdriving the voltage)
Adjustable color LEDs generally have 3 (or more) Red, Green, Blue diodes in a single case and you vary the power on each to produce and average color.
I haven't seen devices with a variety of IR leds in them but it would be easy to make one. At least out to the regions of infrared that Silicon LEDs work in, say 700-950nm ?