According to my understanding you are trying to map input bitstreams to QPSK symbols, but you were unable to find function to do so in MATLAB.
The ‘QPSKModulator’ function from the communication toolbox could be used to achieve this functionality. The following example code might help you.
%Creating Bitstream
bitstream=[0,1,1,1,1,1,0,1]'
%Create QPSK Modulator system object
hMod = comm.QPSKModulator('BitInput',true)
%Modulating input bitstream
modOut = step(hMod, bitstream)
%Seperating real and Imag from Complex type
I=real(modOut)
Q=imag(modOut)
Please refer to this documentation link for more information regarding constellation used by 'QPSKModulator' function to map input bitstreams to QPSK symbols.
or
Type the following command into the MATLAB command window to get more insight.
help comm.QPSKModulator