Landscape figure in LaTeX

This should work for you, without removing "unnecessary" packages:

\documentclass[12pt, oneside]{book}
\usepackage{graphicx}
\usepackage{wrapfig}
\usepackage{lscape}
\usepackage{rotating}
\usepackage{epstopdf}

\begin{document}

\begin{sidewaysfigure}[ht]
    \includegraphics{../figures/pics/DivLibPropProfile}
    \caption{Property profile of the diverse library compared to the compound pool.}
    \label{fig:PropProf}
\end{sidewaysfigure}

\end{document}

This is a general minimal example using rotating

\documentclass{article}
% For rotating figures, tables, etc.
%  including their captions
\usepackage{rotating}

\begin{document}

% A small example on how to use the "rotating" package.
%  Displays a figure and it's caption in landscape
\begin{sidewaysfigure}[ht]
    \includegraphics[width=\textwidth]{figure.png}
    \caption{Caption in landscape to a figure in landscape.}
    \label{fig:LandscapeFigure}
\end{sidewaysfigure}

\end{document}

You can use the angle=90 option provided by graphicx package.

\documentclass[12pt, oneside]{book}
\usepackage[demo]{graphicx}%<----remove demo in your file
\usepackage{wrapfig}
\usepackage{lscape}
\usepackage{rotating}
\usepackage{epstopdf}
\begin{document}
\begin{figure}[ht]
\centering
    \includegraphics[angle=90]{../figures/pics/DivLibPropProfile}%<---angle here
    \caption{Property profile of the diverse library compared to the compound pool.}
    \label{fig:PropProf}
\end{figure}

\begin{figure}[ht]
\centering
    \includegraphics[angle=0]{../figures/pics/DivLibPropProfile}
    \caption{Property profile of the diverse library compared to the compound pool - not rotated.}
    \label{fig:PropProf}
\end{figure}
    \end{document}