<PAGE>
                                                                  EXHIBIT 10.145


                               ASSIGNMENT/ PLEDGE
                              (SECURITY AGREEMENT)

KNOW ALL MEN BY THESE PRESENTS:

         THAT, CRESCENT OPERATING, INC., a Delaware corporation ( "Debtor") for
valuable and sufficient consideration paid, the receipt of which is hereby
acknowledged, hereby TRANSFERS, ASSIGNS and CONVEYS as collateral unto BANK OF
AMERICA, N.A. ("Secured Party"), and does hereby grant Secured Party a security
interest in and to the following described interest in, of and with respect to
limited liability company ("Debtor's Membership Interest"), together with all
rights, titles, equities and interests of Debtor thereunder, including, without
limitation, the right to withdraw capital and receive distributions, and all
money, income, proceeds, guarantees and benefits attributable or accruing to any
of the foregoing or to such membership interest, and all products and proceeds
of the foregoing and all general intangibles and contract rights related
thereto, including without limitation, all revenues, distributions, dividends,
property, contract rights and other rights and interests that Debtor is, or may
hereafter become, entitled to receive on account of any of the foregoing (all
sometimes herein called the"Membership Interest Collateral"), to-wit:

100% membership interest in and to, as the sole Member and Manager of, COPI Cold
Storage, LLC, a limited liability company organized under the laws of Delaware
(the "Limited Liability Company") evidenced by a Certificate of Formation dated
March 11, 1999, and by an Operating Agreement dated March 11, 1999 (the
"Operative Documents").

         Without limiting the foregoing, the Membership Interest Collateral
shall include all of Debtor's rights to return of capital and distributions of
profit, cash flow and other amounts pursuant to the above described Operative
Documents and incident to Debtor's Membership Interest.

         This Security Agreement is being executed and delivered in connection
with that certain promissory note (as it may be modified, renewed or extended,
referred to in this Security Agreement as the "Note") dated as of December 31,
2001, in the face principal amount of $15,000,000.00 executed by Debtor and
payable to the order of Secured Party and Debtor, and the "Loan Documents" (as
defined in the Note and herein so called). This Security Agreement is made to
secure the payment of all indebtedness and obligations of Debtor to Secured
Party evidenced by the Note and the Loan Documents, and the entire "Obligation"
as defined in the "Loan Agreement" (as defined in the Note, with express
reference to such Loan Agreement being made herein for the purposes contemplated
therein) (sometimes collectively referred to in this Security Agreement as the
"Secured Indebtedness"), and upon full payment of the Secured Indebtedness, this
assignment shall be null and void and the Membership Interest Collateral,
together with all liens securing the same, shall, at the expense of the Debtor,
be transferred, without warranty or recourse, to the Debtor by the Secured
Party. (It is expressly noted that the Note is sometimes referred to in the
other Loan Documents as the "Modification Note.")

         Debtor hereby represents and warrants unto Secured Party that Debtor is
the owner of the Membership Interest Collateral and the sole member and manager
of the Limited Liability Company, and that Debtor, acting without obtaining any
approvals or consents not already obtained or provided to Secured Party
simultaneously herewith or further action whatsoever, has the full and
unqualified right and authority to assign and pledge said Membership Interest
Collateral and grant Secured Party full authority and control over the
Membership Interest Collateral in the manner and for the purposes herein set
forth, subject to the qualifications set forth in this Security Agreement.



<PAGE>



         Further, as an inducement to the Secured Party to enter into the
modification and extension evidenced by the Note and as a part of the
consideration therefor, Debtor hereby covenants, warrants and represents unto
Secured Party that:

1. Except for the rights and interests of Crescent Real Estate Equities Limited
Partnership ("Subordination Party") which are subject to a Subordination
Agreement dated as of the effective date hereof executed by Subordination Party
in favor of Secured Party, Debtor has not executed any prior assignment, pledge
or hypothecation of any of the Membership Interest Collateral and that Debtor
holds full and complete rights granted to Debtor under the terms of the
Operative Documents, free and clear of the rights of any third person whosoever.

2. Debtor shall faithfully and fully and in all respects and things do or cause
to be done all acts and things necessary and proper to satisfy all of the terms,
covenants and conditions contained in the Operative Documents at Debtor's cost,
risk and expense. IT IS EXPRESSLY UNDERSTOOD, STIPULATED AND AGREED THAT SECURED
PARTY DOES NOT IN ANY WAY ASSUME ANY OF DEBTOR'S OBLIGATIONS UNDER THE OPERATIVE
DOCUMENTS, AND NOTHING HEREIN CONTAINED SHALL BE CONSTRUED AS IMPRESSING UPON
SECURED PARTY ANY BURDEN, OBLIGATION, LIABILITY OR RESPONSIBILITY OF ANY NATURE
WHATSOEVER UNDER OR ARISING OUT OF ANY OF THE MEMBERSHIP INTEREST COLLATERAL.
WITHOUT LIMITING THE FOREGOING, IT IS UNDERSTOOD, STIPULATED AND AGREED THAT
NEITHER SECURED PARTY NOR ANY SUCCESSOR OR TRANSFEREE OF SECURED PARTY SHALL BE
DEEMED A MEMBER OR MANAGER OF THE LIMITED LIABILITY COMPANY UNLESS AND UNTIL THE
SECURITY EVIDENCED HEREBY IS FORECLOSED OR OTHERWISE REALIZED AS SPECIFICALLY
APPROVED IN WRITING BY SECURED PARTY (OR ITS SUCCESSOR OR TRANSFEREE) AND
SECURED PARTY (OR ITS SUCCESSOR OR TRANSFEREE) HAS SPECIFICALLY ACCEPTED
ADMISSION OR SUBSTITUTION AS A MEMBER AND/ OR MANAGER IN WRITING.

3. No claims, offsets or counterclaims of any nature, at law or in equity,
against Debtor now exist as far as is known by Debtor which would give rise to
defenses against the completion of the covenants under any of the Operative
Documents or incident to the Membership Interest Collateral.

4. Debtor is sole member and manager of the Limited Liability Company. The
Operative Documents evidence the entire governing agreements of the Limited
Liability Company and, except for the First Amendment to Operating Agreement
dated March 7, 2002, a copy of which has been provided to Secured Party, have
not been amended, modified, superceded, replaced, restated, supplemented or
otherwise changed or affected. Debtor shall not, without the prior written
consent of Secured Party, amend, modify, supercede, replace, restate, supplement
or otherwise change or affect the Operative Documents, or cause the same to be
done, or otherwise affect or impair the rights and interests of Secured Party as
contemplated in this Security Agreement. Debtor has the requisite authority to
execute and deliver this Security Agreement, and, further, such execution and
delivery will not contravene or conflict with the Operative Documents, true and
correct copies of which have been provided to Secured Party, or any other
agreement or instrument to which Debtor may be bound, and, further, all
necessary determinations, if any, by any person or entity, and any other
required actions as set forth in the Operative Documents in order for this
Security Agreement and the Loan Documents to be effective have been made and no
approval of any third party is required in order to consummate the transactions
contemplated herein and therein, except for any consent in favor of Secured
Party delivered concurrently herewith.

         In the event of default in the payment of any sums, or in the
performance of any covenants, condition or term, payable or performable by any
party under the terms of the Operative Documents or incident to the



<PAGE>



Membership Interest Collateral or any instrument relating to the same then
Secured Party may elect, Debtor hereby expressly waiving notice, demand and
presentment, to declare the Note and any of the Secured Indebtedness immediately
due and payable in full.

         In the event of default in the payment of any installment, principal or
interest or otherwise, or in the performance of any covenant, condition or term
payable or performable under the terms of the Note or any of the Secured
Indebtedness, in accordance with the terms thereof, or in the event of default
in the performance of any covenant, condition or term hereof or any instrument
evidencing or securing the Note or any of the Secured Indebtedness, or if any
warranty, representation or statement herein or in any other document executed
by Debtor in connection with the borrowing contemplated thereunder proves to be
false in any material respect when made, or if any Default or Event of Default
shall occur under the terms of the Note or any of the Loan Documents, then
Secured Party may elect, Debtor hereby expressly waiving notice, demand and
presentment, to declare any and all of the Note and the Secured Indebtedness
immediately due and payable in full.

         In the event of default in the payment of any of the Secured
Indebtedness when due or declared due, or if any Default or Event of Default
shall occur under the terms of the Note or any of the Loan Documents, in
addition to any other remedies which Secured Party shall be entitled to under
the Note, any Loan Documents or under applicable laws or equity (all of which
shall be cumulative and not exclusive of one another), Secured Party shall have
the right, at its sole option, to sell the Membership Interest Collateral at its
option at either a Public Sale or a Private Sale. Should Secured Party elect to
sell the Membership Interest Collateral at a Public Sale, said Public Sale shall
be to the highest bidder for cash at the Courthouse door of Tarrant County,
Texas, after having given notice of the time, place and terms of such Public
Sale by posting a written or printed notice of said sale at the Courthouse door
of said County at least ten (10) days before the day of sale and after sending
reasonable notice to the Debtor and to such other person or persons legally
entitled thereto under the Uniform Commercial Code of Texas, of the time and
place of the Public Sale, and the Secured Party shall assign and transfer to the
Purchaser at such sale said Membership Interest Collateral, and the recitals in
such transfer shall be prima facie evidence of the truth of the matters therein
stated and all prerequisites to such sale required hereunder and under the laws
of this State shall be presumed to have been performed. The proceeds of the sale
shall be applied, first to the reasonable expenses of the sale, including
reasonable attorney's fees, and then toward the payment of accrued interest due
and unpaid upon the Secured Indebtedness, and lastly, to unpaid principal in the
direct order of maturity, rendering the balance, if any, to the person or
persons legally entitled thereto under the Uniform Commercial Code as adopted in
Texas, but if there by any deficiency, Debtor shall remain jointly and severally
liable therefor. Secured Party shall have the right to purchase at such Public
Sale, being the highest bidder therefor.

         This instrument shall constitute a Security Agreement under the Uniform
Commercial Code as adopted in Texas. Secured Party, in addition to the rights
and remedies provided for in the preceding paragraph, shall have all other
rights and remedies of a Secured Party under the Uniform Commercial Code as
adopted in Texas and the Secured Party shall be entitled to avail itself of all
such other rights and remedies as may now or hereafter exist at law or in equity
for the collection of the Note and the Secured Indebtedness and the foreclosure
of the security interest created hereby and the resort to any remedy provided
hereunder or provided by the Uniform Commercial Code as adopted in Texas, or by
any other law of Texas, shall not prevent the concurrent employment of any other
appropriate remedy or remedies.



<PAGE>



         The requirement of reasonable notice to Debtor of the time and place of
any Public Sale of the Membership Interest Collateral, or of the time after
which any Private Sale either by Secured Party, or at its option, through a
broker, or any other intended disposition thereof is to be made, shall be met if
such notice is mailed, postage prepaid, to Debtor at the address of Debtor
designated in the Note, at least ten (10) days before the date of any Public
Sale or at least ten (10) days before the time after which any Private Sale or
other disposition is to be made.

         Secured Party may remedy any default, without waiving same, or may
waive any default without waiving any prior or subsequent default. The security
interest herein created shall not be affected by or affect any other security
taken for the Secured Indebtedness, or any part thereof, and any renewals,
extensions or rearrangements may be made of any of the Secured Indebtedness
without affecting the priority of this security interest or the validity thereof
with reference to any third party, and the holder of the Secured Indebtedness
shall not be limited by any election of remedies if it chooses to foreclose this
security interest by suit. The right to sell under the terms hereof shall also
exist cumulative with said suit and one method shall not bar the other, but both
may be exercised at the same or different times, nor shall one by a defense to
the other.

         Secured Party shall have the power to endorse and is hereby appointed
Debtor's agent and attorney-in-fact for the purpose of doing any and every act
which Debtor is obligated to do by this instrument and to exercise all rights of
Debtor relating to the Membership Interest Collateral, including exercising,
signing, transferring or delivering in the name of Debtor any instruments or
documents which may be necessary to evidence, perfect or realize upon the
security interest or obligations created by this Security Agreement and to do
all other acts necessary to preserve and protect the Membership Interest
Collateral or to protect Secured Party's security interest in the Membership
Interest Collateral. Debtor authorizes Secured Party, at Secured Party's option,
to collect and receipt for any and all sums becoming due upon the Membership
Interest Collateral, such sums to be held by Secured Party without liability for
interest thereon and applied toward the payment of the Secured Indebtedness as
and when the same becomes payable, and Secured Party shall have the full control
of the Membership Interest Collateral until the Secured Indebtedness is fully
paid, but Secured Party is under no obligation to make or enforce the collection
of the Membership Interest Collateral and the failure of the Secured Party from
any cause to make or enforce the collection thereof shall not in anyway
prejudice the right of Secured Party to thereafter make or enforce collection
thereof or in anyway affect the Secured Indebtedness. Notwithstanding the
foregoing or anything else to the contrary contained in this Security Agreement
or the Loan Documents, prior to notice by Security Party to Debtor otherwise
after the occurrence of any Default or Event of Default under the terms of the
Note or any of the Loan Documents, Debtor shall retain all voting rights and
distributions with respect to the Membership Interest Collateral.

         Debtor agrees to pay in full all reasonable expenses, including
reasonable attorney's fees, of the Secured Party which have been or may be
incurred by the Secured Party in connection with the preparation of this
Security Agreement, the enforcement of any of Debtor's obligations hereunder and
under any document executed in connection with any grant or pledge of security
for the payment of any note or indebtedness contemplated hereunder, and the
recording and filing and re-recording and refiling of any such document.


<PAGE>



         The pronouns used herein shall be construed as masculine, feminine or
neuter as occasion may require. The terms "Secured Party" and "Debtor" as used
herein include, shall bind and shall inure to the benefit of the respective
heirs, executors or administrators, successors, representatives, receivers,
trustees, beneficiaries and assigns of such parties. If there be more than one
Debtor, their obligation shall be joint and several.

         The law governing this secured transaction shall be the Uniform
Commercial Code as adopted in Texas and other applicable laws of the State of
Texas. All terms used herein which are defined in the Uniform Commercial Code as
adopted in Texas shall have the same meaning herein as in said Code.

         ARBITRATION. ANY CONTROVERSY OR CLAIM BETWEEN OR AMONG THE PARTIES
HERETO, INCLUDING, BUT NOT LIMITED TO, THOSE ARISING OUT OF OR RELATING TO THIS
SECURITY AGREEMENT OR ANY RELATED AGREEMENTS OR INSTRUMENTS, INCLUDING ANY CLAIM
BASED ON OR ARISING FROM AN ALLEGED TORT, SHALL BE DETERMINED BY BINDING
ARBITRATION IN ACCORDANCE WITH THE FEDERAL ARBITRATION ACT (OR IF NOT
APPLICABLE, THE APPLICABLE STATE LAW), THE RULES OF PRACTICE AND PROCEDURE FOR
THE ARBITRATION OF COMMERCIAL DISPUTES OF JUDICIAL ARBITRATION AND MEDIATION
SERVICES, INC. (J.A.M.S.) AND THE "SPECIAL RULES" SET FORTH BELOW. IN THE EVENT
OF ANY INCONSISTENCY, THE SPECIAL RULES SHALL CONTROL. JUDGMENT UPON ANY
ARBITRATION AWARD MAYBE ENTERED IN ANY COURT HAVING JURISDICTION. ANY PART TO
THIS SECURITY AGREEMENT MAY BRING AN ACTION, INCLUDING A SUMMARY OR EXPEDITED
PROCEEDING, TO COMPEL ARBITRATION OF ANY CONTROVERSY OR CLAIM TO WHICH THIS
SECURITY AGREEMENT APPLIES IN ANY COURT HAVING JURISDICTION OVER SUCH ACTION.

A. SPECIAL RULES. THE ARBITRATION SHALL BE CONDUCTED IN THE CITY OF THE DEBTOR'S
DOMICILE AT THE TIME OF THIS SECURITY AGREEMENT'S EXECUTION AND ADMINISTERED BY
J.A.M.S. WHO WILL APPOINT AN ARBITRATOR; IF J.A.M.S. IS UNABLE OR LEGALLY
PRECLUDED FROM ADMINISTERING THE ARBITRATION, THEN THE AMERICAN ARBITRATION
ASSOCIATION WILL SERVE. ALL ARBITRATION HEARINGS WILL BE COMMENCED WITHIN
NINETY(90) DAYS OF THE DEMAND FOR ARBITRATION; FURTHER, THE ARBITRATOR SHALL
ONLY, UPON A SHOWING OF CAUSE, BE PERMITTED TO EXTEND THE COMMENCEMENT OF SUCH
HEARING FOR UP TO AN ADDITIONAL SIXTY (60) DAYS.

B. RESERVATIONS OF RIGHTS. NOTHING IN THIS SECURITY AGREEMENT SHALL BE DEEMED
TO: (I) LIMIT THE APPLICABILITY OF ANY OTHERWISE APPLICABLE STATUTES OF
LIMITATION OR REPOSE AND ANY WAIVERS CONTAINED IN THIS SECURITY AGREEMENT; OR
(II) BE A WAIVER BY THE SECURED PARTY OF THE PROTECTION AFFORDED TO IT BY 12
U.S.C. SEC. 91 OR ANY SUBSTANTIALLY EQUIVALENT STATE LAW; OR (III) LIMIT THE
RIGHT OF THE SECURED PARTY HERETO (A) TO EXERCISE SELF HELP REMEDIES SUCH AS
(BUT NOT LIMITED TO) SETOFF, OR (B) TO FORECLOSE AGAINST ANY REAL OR PERSONAL
PROPERTY COLLATERAL, OR (C) TO OBTAIN FROM A COURT PROVISIONAL OR ANCILLARY
REMEDIES SUCH AS (BUT NOT LIMITED TO) INJUNCTIVE RELIEF, WRIT OF POSSESSION OR
THE APPOINTMENT OF A RECEIVER. THE SECURED PARTY MAY EXERCISE SUCH SELF HELP
RIGHTS, FORECLOSE UPON SUCH PROPERTY, OR OBTAIN SUCH PROVISIONAL OR ANCILLARY



<PAGE>
REMEDIES BEFORE, DURING OR AFTER THE PENDENCY OF ANY ARBITRATION PROCEEDING
BROUGHT PURSUANT TO THIS SECURITY AGREEMENT. AT THE SECURED PARTY'S OPTION,
FORECLOSURE UNDER A DEED OF TRUST OR MORTGAGE MAY BE ACCOMPLISHED BY ANY OF THE
FOLLOWING: THE EXERCISE OF A POWER OF SALE UNDER THE DEED OF TRUST OR MORTGAGE,
OR BY JUDICIAL SALE UNDER THE DEED OF TRUST OR MORTGAGE, OR BY JUDICIAL
FORECLOSURE, NEITHER THIS EXERCISE OF SELF HELP REMEDIES NOR THE INSTITUTION OR
MAINTENANCE OF AN ACTION FOR FORECLOSURE OR PROVISIONAL OR ANCILLARY REMEDIES
SHALL CONSTITUTE A WAIVER OF THE RIGHT OF ANY PARTY, INCLUDING THE CLAIMANT IN
ANY SUCH ACTION, TO ARBITRATE THE MERITS OF THE CONTROVERSY OR CLAIM OCCASIONING
RESORT TO SUCH REMEDIES.

NOTICE OF FINAL AGREEMENT. THIS WRITTEN AGREEMENT AND THE OTHER LOAN DOCUMENTS
OF DEBTOR REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF THE PARTIES. THERE ARE NO UNWRITTEN OR ORAL AGREEMENTS BETWEEN THE PARTIES.

EXECUTED and ENTERED INTO to be effective as of December 31, 2001.


DEBTOR:                                   SECURED PARTY:
CRESCENT OPERATING, INC.                  BANK OF AMERICA, N.A.

By:                                       By:
   ------------------------------            -----------------------------------
Jeffrey L. Stevens, President and         Cary C. Conwell, Senior Vice President
Chief Executive Officer