caption of subfloat not fitting on page

Question

In my thesis I have 13 figures I want on a single page. Since the last figure sits at the left side there is some space at the right side I would like to use for the caption. Somehow the caption goes below the figure and some part is chopped off. How can I make the caption use the right side of the last figure. Below is the code and the figure

\begin{figure}[htbp]
  %\centering
 \subfloat[\tiny\textbf{Ip, 0.00kcal/mol}]     {\label{fig:czar1p}\includegraphics[width=0.33\textwidth]{chap2/figs/czar1p.jpg}} 
    \subfloat[\tiny\textbf{IIp, 0.57kcal/mol}]{\label{fig:czar2p}\includegraphics[width=0.33\textwidth]{chap2/figs/czar2p.jpg}}
    \subfloat[\tiny\textbf{IIn, 0.51kcal/mol}]{\label{fig:czar2n}\includegraphics[width=0.33\textwidth]{chap2/figs/czar2n.jpg}} 

:   
:
:
:
 : 
\subfloat[\tiny\textbf{VIIIn, 7.09kcal/mol}]  {\label{fig:czar8n}\includegraphics[width=0.33\textwidth]{chap2/figs/czar8n.jpg}}\\
   \caption{ The thirteen conformers of Cs\"{a}sz\"{a}r \cite{csaszar92} using MP2(full)/6-  311++G**. The nomenclature used here is adopted throughout this text for glycine. The representation p indicates that the heavy atom backbone C(=O)(CN)O is planar and n indicates they are nonplanar. The figure is the relative energy with respect to Ip}
  \label{fig:czars}
 \end{figure}

Thank you in advance.

Answer 1

I used a simple \parbox to place the caption (I used the demo option for graphicx to make my example compilable for everyone; do not use that option in your actual code):

\documentclass{book}
\usepackage[demo]{graphicx}
\usepackage{subfig}
\usepackage{caption}

\begin{document}

\begin{figure}[htbp] %
\subfloat[\tiny\textbf{Ip, 0.00kcal/mol}]{\label{fig:czar1p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar1p.jpg}}\hfill
\subfloat[\tiny\textbf{IIp, 0.57kcal/mol}]{\label{fig:czar2p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2p.jpg}}\hfill 
\subfloat[\tiny\textbf{IIn, 0.51kcal/mol}]{\label{fig:czar3n}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2n.jpg}}\\
\subfloat[\tiny\textbf{Ip, 0.00kcal/mol}]{\label{fig:czar4p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar1p.jpg}}\hfill 
\subfloat[\tiny\textbf{IIp, 0.57kcal/mol}]{\label{fig:czar5p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2p.jpg}}\hfill 
\subfloat[\tiny\textbf{IIn, 0.51kcal/mol}]{\label{fig:czar6n}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2n.jpg}}\\
\subfloat[\tiny\textbf{Ip, 0.00kcal/mol}]{\label{fig:czar7p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar1p.jpg}}\hfill 
\subfloat[\tiny\textbf{IIp, 0.57kcal/mol}]{\label{fig:czar8p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2p.jpg}}\hfill 
\subfloat[\tiny\textbf{IIn, 0.51kcal/mol}]{\label{fig:czar9n}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2n.jpg}}\\
\subfloat[\tiny\textbf{Ip, 0.00kcal/mol}]{\label{fig:czar10p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar1p.jpg}}\hfill 
\subfloat[\tiny\textbf{IIp, 0.57kcal/mol}]{\label{fig:czar11p}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2p.jpg}}\hfill 
\subfloat[\tiny\textbf{IIn, 0.51kcal/mol}]{\label{fig:czar12n}\includegraphics[width=0.32\textwidth]{chap2/figs/czar2n.jpg}}\\
\subfloat[\tiny\textbf{VIIIn, 7.09kcal/mol}]{\label{fig:czar13n}\includegraphics[width=0.32\textwidth]{chap2/figs/czar8n.jpg}}\hfill
\parbox[b]{.6\textwidth}{\caption[caption for the LoF]{The thirteen conformers of Cs\"{a}sz\"{a}r \cite{csaszar92} using MP2(full)/6-311++G**. The nomenclature used here is adopted throughout this text for glycine. The representation p indicates that the heavy atom backbone C(=O)(CN)O is planar and n indicates they are nonplanar. The figure is the relative energy with respect to Ip}}
\label{fig:subfigures}
\end{figure}

\end{document}

EDIT: I've modified my code according to Axel Sommerfeldt's comment.